Tishabet

Heat related breakdowns, but doesn't seem to be vapor lock...

Recommended Posts

Hi guys,

I am having a persistent problem with my '38 Special that has left me broken down several times now. I have tried several things to fix the issue, but nothing has worked so far... as evidenced by a breakdown just today. So, I'm turning to the collected wisdom of you guys to see if you have any ideas. I have detailed each breakdown and fix below, but bottom line is that my engine is dying after driving the car for 10-30 minutes.

The car: Bone stock '38 Model 41 with the 248CI straight eight. Tank is full, using 87 octane pump gas with some lead additive and a bit of sta-bil. Engine has approximately 100 miles on a total rebuild.

Breakdown #1:

This summer is the first time I have taken my Buick out for more than a spin around the block. Last Friday, I took the car from the garage where I store it to my home, a trip of approximately 20 miles. The weather was in the low 90s and humid, but I was on surface roads and was doing a steady 35 mph or so. After entering my town I hit a number of stoplights and some traffic, and the temp started creeping up. At one intersection I was stopped, and when it came time to go I hit the gas and stalled the car... not sure if I legitimately stalled it (via letting the clutch out too fast) or

if the engine chose then to quit. In any case, I could not get the car re-started. This was about 30 minutes into my trip. I pushed it out of the intersection and while pushing it the engine boiled over, leaving a bit of water in the street. I got it into a parking lot and tried without success to get the engine to re-start. Finally, after a wait of about 1/2 hour I got it going. Engine was at a normal temp, and after driving it around the parking lot a bit to make sure everything seemed OK I decided to hit the road again. I pulled out onto the road and made it about 100 feet before the engine started sputtering and missing as if it were running out of gas, then quit. I pulled into yet another parking lot and left the car there while I went to a local restaurant and got dinner. About two hour later (past dark, now around 80 degrees) I got the car started and drove it the rest of the way home without an issue.

Fix #1:

I decided due to the heat I was having a problem with vapor lock... the symptoms and circumstance seemed correct. After reading up on this forum, I placed an order for a 6V fuel pump to install near the engine, and also purchased a gallon of kerosene. I added 1/2 of the gallon of kerosene to the fuel.

Breakdown #2:

Two days after breakdown #1, I took the car out to drive back to its garage. The 6V fuel pump was still in the mail and was not installed, only difference this day was the kerosene in the gas. This time I barely made it out of town before I broke down, approximately 5 minutes into my drive. This time I was driving at normal speed (35mph or so) and the engine suddenly started to miss, then died as if it had run out of gas. Water temp at this point was about mid-point on the gauge... definitely not overheating. I tried to get it started but no luck, so I called AAA and got a tow to my garage.

Fix #2:

The fuel pump arrived and I installed it. The pump is located just in front of the gas tank per recommendation here. I also bypassed the steel line running from the junction just above the diff to the area of the battery and instead used a new piece of rubber fuel line (routed along the original fuel line route) all the way from the pump to the piece of steel line entering the mechanical pump. I left the mechanical pump "in-line" so that I can run the mechanical pump normally and the electric pump only when needed.

Breakdown #3:

This morning I finished wiring the pump and decided to take the car for a spin to see if it fixed the issue. I had the electric pump running for the entire drive. About 10 minutes into my drive, and identical breakdown... car driving at normal speed, engine sputters and dies as if there is no fuel. This is puzzling and frustrating... I figured my problem had to be vapor lock, and the 6V pump is supposed to be the fix but alas the problem seems unchanged. Once again the operating temp was normal (middle of gauge) when the breakdown occurred. After letting the car rest about 10 minutes I was able start it, and headed back to the garage. About 1/2 way there broke down again. Another rest (more like 20 minutes this time) and I was able to restart and get the rest of the way home.

Fix #3:

I decide maybe my coil is faulty so I replace it with another one I have on hand. The one I replaced is a 6V generic from Bob's, the replacement part is a "flame thrower" from pertronix. Not a "correct" part but I figured it would eliminate the possibility of the coil being the issue.

In garage breakdown:

Having replaced the coil, I decide to see if I can cause the problem to occur in the garage and save myself the trouble of breaking down on the road. I started up the car and moved the throttle up to driving RPMs. The electric fuel pump was running. As the engine heats up to normal operating temps the engine seems to be missing a bit... you can hear it standing next to the car, and back at the tail pipe each "miss" feels like an extra strong puff from the pipe. After running at a good clip for 10-15 minutes the engine sputters and dies, same issue as before. Engine is not overheated, temp is in the center of the gauge.

Any ideas?

Share this post


Link to post
Share on other sites

Grant,

I suggest you double check the valve clearances to address the intermittent puffing from the tail pipe. Check the timing too. It sounds like it may be too retarded which can also cause overheating.

Then drive your car to Shaw Farm Dairy in Dracut for an ice cream! Tell them I sent you...

Share this post


Link to post
Share on other sites

Hi Grant.

Our 39 coupe went through something similar with regards to the overheating. We found that getting a few more miles on the engine sorted the majority of the heating problems. Still runs a bit warm, but when we connect the heater up, we'll fit a smaller diameter water pump pulley (it has a 47 one) and put some water wetter in it.

How's your thermostat? Opening up ok? Agree with Mark re the exhaust valve clearances. I would have suggested a valve grind if your engine wasn't fresh.

Cheers

Grant

Share this post


Link to post
Share on other sites

Well, I hope he is going to make it to the Shaw Farm Dairy in 2011 with the Pre-War after tour, plus other fun stuff.

That will give him plenty of time to sort out the overheating problem.

John

Share this post


Link to post
Share on other sites

Hi Grant.

I had a similar problem with my 1950, Mod 41 D, 248. Same as yours, after changing fuel pump with a known good one, he still quit! Would start and run as long as I introduced gas into top of carb. Mine is a stromburg with the round flat morain filter at the carb. Turns out this was the bottleneck. It acted just like yours after setting for awhile, it would start. Presume enough gas would work through the pluggage, which looked like black carbon deposits, to start and run for a short time. Then die. I cleaned the filter by soaking in solevents and flushing until it was reasonably clean. THEN instaled an inline filter just ahead of the fuel pump. I have driven about three hundred miles since with no more stalling. Tomorrow will be the real test as I head for Ames.

I will bet you a doughnut it is fuel, somewhere. Good luck,

Ben

Share this post


Link to post
Share on other sites

Have you done a fuel line pressure test where it goes into the carb, This will tell you if you have a blockage or a kink some were in the line.Good luck. Bill WEB 38

Share this post


Link to post
Share on other sites

1. How old is the fuel? - perhaps try a fresh tank of gas if its been in there longer than a couple of months, forget the kerosene, maybe try a higher octane

2. If you can, take the air cleaner off when it falters and operate the carb linkage to see if the accelerator pump squirts fuel into the carb throat, at least you then know if the carb is kept supplied with fuel.

3. On the ignition side as you have already replaced the coil; again when it falters, lift the distributor cap off and with the ignition turned on, manually open and close the points, you should see a healthy spark at the points (you may need to shade the area if you are in bright sun light). A weak spark is indicative of a failed condensor, this may occur as engine temp rises.

Share this post


Link to post
Share on other sites

Hi guys,

thanks so much for all of the responses!

Just to be clear, I am breaking down because the engine quits running... I'm not voluntarily shutting down the engine due to overheating.

As far as overheating goes, the engine might still have a tendency to overheat and I will definitely be tracking that down as it will be an issue for summer touring. I checked the timing and vacuum advance last summer with a timing light, but will check again to see that nothing has moved and the vacuum advance is still working correctly. I will also check my valve clearances again... I did this once a couple of years back, but that was before the engine was running so now that I have some driving time on the rebuild it is probably a good idea to see if everything is still in spec. I also have heard (similar to the "other" Grant's observation) that I should expect the engine to run a bit hot until I have a thousand miles or more on the rebuild. Thermostat is a 160 degree unit and seems to be operating fine.

All that being said, I'm thinking that overheating is not really the issue as these two most recent breakdowns occurred when the engine was operating at fairly normal temps. It still seems the problem is probably heat related, but I don't have to overheat the engine to get it to break down... it will happen just fine at normal operating temps :-P

I'm leaning toward a fuel problem, simply because the issue is so sudden and absolute... the engine goes from chugging right along to just conking out, just like if it had run out of gas. I would think that an electrical or timing problem would cause the engine to run poorly or not want to keep running, but in this case it is running like a champ until it quits. The only heat related ignition issue I know of is the coil, and that has been eliminated by replacing the coil.

I have not checked the fuel pressure as I do not have a gauge, but I might invest in one to troubleshoot. The fuel filter in the mechanical pump looks good, but I will check it more closely. Currently I have an in-line glass filter just before the mechanical filter which also looks fine, and there is another filter just before the electrical pump. This filter came attached to the pump so I don't think it is related to the issue as it was not on the engine until this most recent breakdown. My carb is a stromberg aerotype AAV-1 and has no integral filter. I rebuilt it myself around three years ago, acceleration pump seems good and the car starts easily and idles smoothly and well. I drained all of the gas from the tank when I installed the electrical pump, so the gas that was in the tank when I broke down today is only days old and has no kerosene added, only the lead substitute and the sta-bil.

One possibility I am considering after some reading here is carb temp... I noted that the air cleaner was very hot to the touch when I removed it today, and when I touched the carb it seemed pretty hot to me. It was cool enough that I could keep my finger on it, but was still pretty hot. I am not positive that the carb heater is working correctly, and might try to disable it entirely as I don't really drive in cold weather. I have an "insulator" installed between the carb and the manifold, but no heat shielding is in place between the carb and the exhaust manifold.

Another thing I noticed is that there are occasional bubbles that seem to be coming through the fuel filter I placed just before the mechanical fuel pump. Right now I have the original fuel line going from inside the tank to the junction right above the differential, where it is feeding the electric pump and then after that I am using new rubber line all the way to the filter where I have observed the bubbling. Perhaps I can a pinhole leak in the original line going to the tank?

Mark, the wife and I love Shaw's... I will be bringing the Buick there regularly as soon as I figure out this issue!

Thanks again guys!

Edited by Tishabet (see edit history)

Share this post


Link to post
Share on other sites

OK so we have eliminated the fuel quality, how about the gas tank vent?

Does the accelerator pump squirt fuel when it stops?

The ignition condensor is just as prone to heat failures as the coil.

Share this post


Link to post
Share on other sites

It also could be a faulty ignition switch, or wire. Fair connection when it is cold, bad connection when it heats up. Dandy Dave!

Share this post


Link to post
Share on other sites

Wow, I love the gas tank vent theory. Same thing happened to our Boy Scout bus. The next time you have an issue, go to the tank and pull off the filler cap. If you hear air rushing in, this may be your problem. I found a new cap at my local auto parts store that vents in both directions. Let's air in as the gas is consumed, and let's air out due to expansion on a hot day.

Share this post


Link to post
Share on other sites
OK so we have eliminated the fuel quality, how about the gas tank vent?

Does the accelerator pump squirt fuel when it stops?

The ignition condensor is just as prone to heat failures as the coil.

The friendly cop who stopped to chat before my tow showed up suggested gas tank vent as well. My gas cap (a generic replacement from Bob's or Kanter) says "vented" on the top and I did not get a "whoosh" when I opened the tank. Nonetheless, I decided to eliminate this as a possible source and sacrificed the cap to the ventilation gods by drilling a small hole right through the thing.... it is vented for sure now :-P

Unfortunately my most recent breakdown occurred with my "uber vented" cap in place, so I don't think that's the issue.

I did not check the accelerator pump just after a breakdown... if the gas is boiling in the carb, should I be able to see it dribbling down the throats of each barrel as if I was actuating the pump?

Hadn't thought of ignition condenser... I will replace mine to see if that makes a difference.

Thanks for the suggestions guys!

Share this post


Link to post
Share on other sites

Hey guys,

Quick update here as I had time to work on the car yesterday afternoon. First thing I did was replace the condenser in the distributor with a new one. Next I warmed up the engine and re-checked valve clearances... almost all were in spec, a couple were a bit tight so I adjusted them. Next I checked the timing and timing advance with a timing light, and everything was in good shape there.

I decided to see if the work I had done (specifically the condenser replacement) had made any difference with my hot breakdown issue, so I started the engine and moved the RPMs up to a speed I would normally associate with about 35MPH in third. The car ran with the same intermittent miss that I had been experiencing before... more on that later. Engine was up to about 180 after 10 minutes of running this way, and slowly edged closer to 200 over the next 10 minutes for 20 minutes of overall running time. In my past experiment this had been sufficient time for the engine to experience its running/heat related breakdown, so I am thinking the condenser may have been the issue. I will try to find some time tonight to take the car out for a lengthy drive and see if it acts up.

Three issues to tackle:

1) Engine cooling. As far as overheating, the engine was just around 200 after 20 minutes of fairly high RPMs with no air movement other than that of the fan, i.e. I was not actually driving the car so it would be missing some cooling benefit this way. After returning the car to a normal idle for 2-3 minutes, the engine stayed just shy of 200. When I shut the engine off the radiator boiled over. Should I be concerned about this, or do you think this is a reasonable level of cooling given the condiitons (specifically, high RPM with no car movement)?

2) Exhaust leak. I have found that the seal between the exhaust manifold and the exhaust system has a pretty significant leak. This would probably be raising the under hood temps pretty significantly, no? I had noted that the carb seemed quite hot during my last breakdown, maybe this is why?

3) Carb. Looking down the barrels of the carb while the engine is running at a good clip, the barrel closest to the engine seems to be metering out more than then barrel furthest from the engine... a visible dribble versus intermittent drops. Perhaps this is why the engine is missing and possibly overheating as well... half the cylinders seem like they are not getting enough gas so they would be running lean.

Share this post


Link to post
Share on other sites

Does your Buick have a heat riser valve in the exhaust manifold or below it? Check to see if it is stuck closed. This can cause overheating symptoms and is often overlooked.

Share this post


Link to post
Share on other sites
Does your Buick have a heat riser valve in the exhaust manifold or below it? Check to see if it is stuck closed. This can cause overheating symptoms and is often overlooked.

You mean the "flapper" valve that is supposed to heat up the carb when it is cold? If so then yes, my car is equipped with one. I have verified that it is free to move but have not otherwise checked its function... I will do so.

Share this post


Link to post
Share on other sites

Not out of the woods yet it seems, I would not be happy with the temp at 200 at any time.

You need to sort that one as a priority before going any further and obviously the first place to start will be the radiator.

Drain it then leave the bottom hose off, put a bung in the bottom outlet, fill the radiator then pull out the bung; the water should rush out, if it glug,glug,glugs then you need to clear out the radiator one way or another.

Trying to sort heat related running faults is difficult if you cant keep the engine at normal operating temps, of course there may be other reasons for hot running but start with the most obvious first.

Share this post


Link to post
Share on other sites

Hi,

Another 2-cents worth, based on experience.

My LaSalle ran hot enough to melt lava on the hood, and of course it would not start when hot and it vapor-locked like crazy. So I had the radiator re-cored (badly needed) and jammed the thermostat-controlled shutters on the radiator wide open. Checked timing, advance, looked for flapper valve (none, but I learned about that with a Studebaker Hawk that I once had--another story...), heat-shielded the fuel line, installed rotary electric fuel pump, etc. I considered an electric radiator fan, but a pos-ground 6-volt fan wasn't easily available. (This was before development of the internet...)

It's when I finally drained the coolant at the lower radiator hose to replace it with an efficient 50/50 solution that I noticed that the system is supposed to hold 14 quarts, but only about 6 or 7 came out. Hmmmmm. I opened the drain cocks on the block--nothing came out. Hmmmm again. Finally popped one of the flat heads off--and I found that the water jackets were packed SOLID with what appeared to be brown concrete. In point of fact I concluded as I chipped it all out slowly with a humungous screwdriver, a hammer, and a garden hose for a steady wash, it was massive amounts of Stop-Leak stuff.

Apparently a previous owner had tried to deal with the leaking radiator with bottle after bottle after bottle of Stop Leak. He effectively ruined the car as far as usability went. No water was going around the cylinders, or anywhere through the block for that matter. Only the heads were getting any cooling effect at all. I am surprised the block didn't warp or break.

The point of all this is, if someone put Stop-Leak in your engine in the past, you may have highly restricted water jackets in the block. Try draining the block through the drain cock(s). Remove the cock(s) and probe the opening(s) with a wire and see if you find and can scrape concrete. Ultimately you can pull the head and check the water jackets manually--and order a pizza for later, because that's a fair amount of work and more than you'll do in an afternoon.

Please keep us all posted as to what you find. Your car's ignition and temperature issues are of great interest to us all.

--Tom

Share this post


Link to post
Share on other sites

Good Morning All: These type of problems are hard to figure out. My RULE is that if the car stops suddenly, with no chugging which indicates using all the fuel in the carb, it is an electrical problem. I have been well served by following this rule for many years, with very few exceptions. Assuming the car stops dead with no warning then start at the ignition switch with a test light and work your way through the system immediately, without letting it cool. It could easily be simply a loose wire and check each regardless of the test light result. After doing this check the adequacy of the spark coming out of the distributor. The test light does not tell you the adequacy of the spark. Remember there is a condenser in the distributor which much function properly to store electricity. There could even be a loose wire or short in the distributor or an open circuit anywhere in the system, even under the sheath or wire covering. An open circuit means a loose or broken wire which will not allow the completion of the circuit. For example, I once had problems with one of my 1940's only to find that the wire which runs from the coil to the distributor was loose at the coil outlet. Because it is protected by a rubber cover I could not see that it had worked out enough to create an open circuit. It was hard to push in and this prevented me from making it secure when doing the installation. 95% of the time the problem is a matter of finding a simple problem. Just keep thinking and looking. PLEASE post a message telling us what the problem was after you unravel it. Thanks, Patrick W. Brooks

Share this post


Link to post
Share on other sites

I'm hoping to get some more time in with the car tonight, don't worry I will definitely keep you guys in the loop with what I find!

For what it's worth, I did the "shade tree radiator test" a few years back by taking it out of the car, plugging the bottom fitting, filling it with water, leaning it back at a 45 degree angle and then pulling the plug... the water shot out of there with lots of velocity, which I am told means my radiator itself is _probably_ good.

I have not taken out the freeze plugs in this engine, but did run water through the block and drained both via pump fitting and the drain located near the distributor... water seemed to flow well, nothing nasty came out. I have some new freeze plugs on the way from Bob's so I will probably end up going after the block with my pressure washer if the situation does not improve.

Share this post


Link to post
Share on other sites

On my 36 Pontiac I had a simular problem and it took me years to find it. The wire from the ignition switch to the coil, runs through a steel cable to the bottom of the coil. The old wiring was frayed inside the cable and would short out against the steel casing. When taking off after it was warm it would move just enough to short and start fluttering and then finally stop. Probally a long shot but another thing to look at. I hope you find it and it doesn't take years as it did me. It makes it to where you never want to drive it always fearing you going to break down. Good luck and keep us posted.

Share this post


Link to post
Share on other sites

OK so the condensor has probably cured the engine quit issue - I would give it a hard run to be absolutely sure.

As to overheating - the radiator flow a year or two back? how is it now? - block flow appears good - timing is right - thermostat is good - mixture is good (no coughing/spluttering).

What do you know about the water pump? is the impellor in good order? can you see the flow in top of the radiator with the engine running? - get the temps at normal operating conditions and run the engine at high rpm with the cap off, you should see a quite turbulent flow through the top of the radiator indicating that the pump is effective.

One other thing, again with engine at normal temps feel the top hose and then the bottom hose, there should be a significant difference in temp between the two indicating the overall effectiveness of the radiator.

Share this post


Link to post
Share on other sites

One of those no touch infra red temp guns work great for getting temp readings anywhere on the engine.

Share this post


Link to post
Share on other sites

I have a '36 Century that is doing the same thing. Last year it ran fine. I took it in for a tune-up plugs, points , cap, condenser and rotor. since then it had problems. I figured it had to be fuel becaue the ignition parts were replaced. I've replaced the electric fuel pump, the cars fuel pump and the fuel filter with no luck. I had them put back in the ignition parts that were taken out because it worked with them before, thinking maybe one of the parts were bad. No luck. I'm going to have the coil replaced and hope that works. Next a rebuilt carb. It will run fine for 2-3 miles and act like it's running out of gas and after sitting for 5-10 minutes will start and run for another 1-2 miles and repeat. Frustrating to say the least.

Share this post


Link to post
Share on other sites

Tishabet,

Get. That. Radiator. Boiled. Out. Not trying to sound snotty or mean, just don't even think twice about it. If it's original and you dont KNOW the entire history, I BET they'll find junk in there and it'll run better. I thought mine was good too with the "shade tree radiator test". Yeah, that's why its called that. Purely useless. My entire problem was the radiator. Things pointed to and away from it, but they found a small leak, and "a little crap in there". Must have been more than that, or just enough clogging several cores because after doing that it went from a behavior similar to yours to running 140-160 degrees *all the time* no matter what driving conditions, below about 85 degrees outside. Even in 90+ degree heat, it refuses to shoot up and slooooowly climbs towards 190 or so but will not boil over ever either.

I learned from another vehicle as well as the '38 that the fill it and let it flow test is useless. Truth: You do NOT need all or most of the cores free for it to "flow well". Was weird to find out, but its definitely true. You probably have enough blocked so that it flows easily but flowing easily doesnt mean it's getting cooled. ;)

Share this post


Link to post
Share on other sites

Hi,

If you can stand another thought on this, I recall that there was discussion o n the forum a year or two ago about the button-style bypass valve that is located at or just engine-side of the thermostat housing. It's just a little guy--a coin-size as I recall. The gist of it was, if that valve is open due to damage, or deteriorated cotter pin that holds it together, or some other cause, the engine overheats.

When I had a new core put in the Monster's radiator last year, I paid special attention to this little button valve which consisted of a shaft, a button head, a spring, and a cotter pin. The cotterpin had corroded away. The other parts were brass, and I used a stainless cotter pin to assemble the spring on to the shaft.

I'll check my Motors book to see if there's a diagram of it. A picture's worth a MILLION words. (Inflation, you know....)

--Tom

Edited by trp3141592 (see edit history)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now