Jump to content

Why Is My Old Car Overheating Under Load?


Guest Paterson Chris

Recommended Posts

Guest Paterson Chris

For the past year I've been slowly resurrecting my old ranch find -- a '22 Paterson. Currently I'm trying to address why it's overheating under load. It idles fine in the front yard for long periods but as soon as I get behind the wheel and motor off, the radiator starts to boil over and the engine starts laboring within about a mile. If I pull over and just let it idle, the temperature then drops back to what appears on my motometer as normal. If I take off again, then it starts to overheat same as before. Why is this?

For background information I'll add this:

All cylinders have the same compression. Oil in the crankcase is not discolored and the same with the coolant in the radiator. Cooling sytem was thoroughly flushed last summer. A vacuum gauge attached at the intake manifold shows its pulling a vacuum of 17psi (here at an elevation of 3000ft). Seems to idle fine with no misfiring. Carb is currently tuned to run slightly rich.

Some may jump in to tell me that the timing may be off but I don't think so. Other than the slight movement allowed when using the spark advance/ retard lever, there's no way to radically alter the timing unless I were to physically remove it and re-engage it where the gear meets with different teeth. So a timing issue feels unlikely.

The only thing I can think of that I still haven't touched yet is checking the valve adjustments. Could that be a cause?

Can anyone suggest other causes?

A final note: The muffler looks all original (cast end fittings and such) but I noticed that the tail pipe coming out of the muffler is only about 2/3rd's the size in comparison to the one that enters it. Odd. I've never seen that before.

Thanks --

Chris

post-52760-143138007182_thumb.jpg

Link to comment
Share on other sites

A couple of things to check:

First, if you are forced to use deathanol, rather than real gasoline, the less energy of the deathanol may be causing a lean condition, even though the carburetor is adjusted "rich".

Second, there was an aftermarket carburetor fuel valve design that worked fairly well for carburetors using fuel pump pressure, but poorly for those with gravity feed.

And adjusting the fuel level in those carburetors is somewhat difficult.

You might look at the type of fuel valve, and the float adjustment.

Jon.

Link to comment
Share on other sites

I still think it would be a good idea to check everything about the ignition timing. What brand of system is it? look it up in dykes and see how you check it. There has got to be a way to check it and set it. Less likely but still possible would be your valve timing. Use a degree wheel and measure the opening and closing of your intake and exhaust valves and compare it to specs. I would check your muffler to see if it has a serious obstruction. Maybe you got a rat's nest in it. The size of the outlet pipe should not be enough to plug it up enough to make it overheat.

Link to comment
Share on other sites

I had a similar problem with a Big Six Studebaker I once owned. I set the timing over and over and swore up and down that the timing was right on... The beast would overheat within 1/4 mile. I then advanced the timing little by little until the engine would kick back at start. Then I backed off little by little until it would start easy without spark knock. The car never overheated again. Not very scientific, but it did the job...

Frank

Link to comment
Share on other sites

Guest Paterson Chris

Okay, possible clogged muffler -- I'll check on that as it's easy to do.

Engine is a Continental 6 (model 8R) fired off with a Delco ignition system. Points, condenser, coil (new 6 volt), wiring, and plugs also check okay. As for the timing at the distributor, the only way to further adjust it would be, again, to remove it, rotate the shaft, and re-insert. Not having any maintenance manual (other than my 1925 copy of Dyke's and a Continental 8R parts catalog) I'm reluctant in the extreme to do that. I understand the logic though. I just feel like I'd be going down a slippery slope of bad to worse.

Chris

Link to comment
Share on other sites

Guest simplyconnected

What about your water pump? Is it circulating coolant around all the cylinders? You might want to get a cooking thermometer and check different areas of the block. If you find one area that's hot, maybe one of your ports might be blocked. Idle-speed circulation tends to equalize temps.

Link to comment
Share on other sites

Guest Paterson Chris

Okay, block temperature differences. Thanks, I'll check on that too. My neighbor has one of those hand-held infrared thermometer things so I'll borrow that. In the meantime...

With the mention of the ignition system, you guys have me focusing on that. On a hunch, I went in to the garage, popped off the distributor cap, and checked rotor movement. Guys, there appears to be some backlash in that department. I'm able to rotate it back and forth by, I'm guessing, as much as 8-12 degrees. How much rotor backlash -- if any -- is acceptable? I'm guessing that with the backlash found in this area that the ignition is not advancing as far as it should? My own maintenance notes remark that the distributor shaft actually has a slotted eccentric at the end of it and not a gear as I thought. Do you think cleaning up some of this sloppy wear here will make enough of a difference?

Chris

Link to comment
Share on other sites

Guest simplyconnected

While ignition timing is important, I surmise your cooling capacity is of greater importance, noting that your engine would run slightly hotter with a lean mixture and/or advanced timing. Usually, with timing/mixtures issues, you can hear pinging, knocking, or piston slap. It is audible.

Mechanical load (laboring) would certainly raise the temp, but so what? Shouldn't an engine labor for long periods, like during mountain climbing?

The cooling capacity issue bugs me. Like stiring a pan of soup, boiling takes longer to attain with good flow than if it were sitting stagnant on a hot element. With little flow, it would boil at the hotest points, in this case, at the cylinder hot spots. Boiling anywhere, is still boiling. That's why I would look at coolant flow AND air flow through the radiator.

Is it possible, there could be a big 'bubble' in the engine? Got any way to purge all the air out, then make sure the liquid level is at max?

I suspect, a blocked exhaust would slow the engine a lot, and make it very inefficient, preventing high rpm's, like a carbon-built-up 2-cycle exhaust. But I don't know that it would cause overheating. (Same with incorrect valve lash.)

I saved this for last because it's the most UNpopular idea; are you sure a head gasket isn't leaking pressure into your coolant? That would look like a boiling radiator, and it might not happen during idle. A cracked casting would do just that after heating and expanding, too.

Link to comment
Share on other sites

Guest Paterson Chris

Simplyconnected --

You make some good points. After I address the timing issue I'll look further at the cooling sytem.

Sure, there could be some sort of "bubble" but how are you sure it can be purged? Also, wouldn't the engineers have designed it so that there could be no possibility of a bubble?

The radiator is still the original honeycomb type. I patched some pinholes at the top last summer (and so far still no leaks) and flushed it till it ran clear first with hot vinegar followed by tap water from the garden hose. As for how much scale is left, I simply can't know. It's too bad they can't be rodded out and our local radiator shops have zero interest in touching mine. I once read that dilute muriatic acid is great for truly cleaning your cooling sytem but I'm wondering if that wouldn't be too drastic? The fumes alone are deadly enough. Or Drano? On the other hand, if after addressing everything else I still have to buy a new radiator core, then maybe it wouldn't matter if I use something really potent to clean the cooling system? In the meantime I'd like to keep everything as original as possible (if I replace the radiator core I'd have a hard time justifying the purchase of a new honeycomb type anyway) because I think there's something to the saying, "it can be restored many times over but it's original only once".

Air flow looks to be okay -- the core is not greasy or clogged with dirt anywhere. It does have a new fan belt that I've checked for slippage and also for not being too tight.

Link to comment
Share on other sites

Guest imported_JPIndusi

The classical causes for running hot at speed are:

1. A collapsing radiator hose on the suction side of the water pump, that is, the bottom hose that goes to the water pump (assuming your vehicle has one and is not cooled by convection), and

2. Retarded ignition timing.

The lower hose on most cars has a coil spring inside it to prevent the suction caused by the pump from causing the hose to collapse on itself thereby slowing the coolant flow.

Do you have a specification and procedure for setting the timing using a timing light or a mechanical procedure based on the position where the points are just opening?

Checking the muffler is also important especially for a car that has sat for so long.

Good luck:

Joe, BCA 33493

Link to comment
Share on other sites

Guest simplyconnected

I have GREAT respect for hydrochloric acid. You mentioned 'fumes', but I'm here to tell you, it removes rust right before your eyes. Most people buy it from Home Depot in the semi-diluted form of, Muriatic Acid. Even THAT will etch glass and brick. Do not use it in your radiator, in ANY concentration. It's too corrosive and hard to judge, especially in places you can't see.

I like the idea of using vinegar. We use it in a heated form for our coffee pots, and it works well. What about the stuff people use for their bathrooms; lime-away or CLR? I don't know what that will do in your radiator, but maybe someone else does. Keep crystal drain-o away, it's far too corrosive, and uses aluminum as a catylist to speed violent reactions and heat.

I understand your honeycomb radiator is NOT pressurized and you are at 3,000 feet. That's two disadvantages because your boiling point is now below 212*F, demanding your cooling system work more efficiently. Your only salvation is a large heat exchanger (radiator), plenty of flow. and lots of system coolant (50/50 antifreeze, NOT WATER).

I mentioned the 'bubble' with the idea that if you have a head gasket leak, for example, and it was pushing gasses into the middle of your block's water jacket, gas would displace any liquid, and appear like boiling coolant. Normally, a head gasket leak would suck pressurized coolant into the cylinder, and appear out the exhaust as steam. But, liquid is 800 times more dense than gas at atmospheric pressure. Under compression (engine load), gas could easily inject into a amall water jacket crack.

I am interrested to know your temperature readings, surrounding your cooling system, including your radiator. - Dave

Link to comment
Share on other sites

Guest simplyconnected

Did you ever clean carbon off old pistons? It's a nasty pain, especially in ring grooves. I found, by brushing-on muriatic acid, that black soot and white powdery crap breaks down in no time, and comes off VERY easilly. With a little water-rinse and a soft brush, there's no scraping.

Link to comment
Share on other sites

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Paterson Chris</div><div class="ubbcode-body">

Cooling sytem was thoroughly flushed last summer. </div></div>

I have never seen the core of a hunnycomb radiator. Is this similar to a top flow style with thin tube openings at the top tank? If so I might suggest you pull the radiator and flip it upside down and back flush the unit again. When I started to drive my 56 Buick after a long term generally inactive period, I found my newly recored radiator was blocked by a lot of sediment that got washed up from somewhere. At that time I pulled the radiator and had it flushed again, and then I installed a coolant filter in my top hose. That filter caught more junk than I could believe. I included a picture of the filter I bought but I heard othes have stretched pantyhose over the top hose mount and it worked just fine to catch the big stuff.

post-32834-143138007733_thumb.jpg

post-32834-143138007734_thumb.jpg

Link to comment
Share on other sites

Guest Paterson Chris

Thanks for the replies, guys. I think I have it mostly licked. The timing was off and running mostly with a retarded spark. I readjusted everything starting with the mark at the flywheel, piston #1 at TDC, etc. and reset the distributor cam via a screw adjustment I hadn't seen before. It now starts easier and the engine ended up running faster so I had to turn down the idle speed adjustment screw on the carb as well.

This makes having the internet worth it.

Chris

Link to comment
Share on other sites

  • 2 weeks later...
Guest imported_tigermoth

it sounds like you are getting a handle on this. good for you. one other idea..are your brakes adjusted and working poperly. a dragging brake will cause the over heating as well. regards, tom

Link to comment
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
×
×
  • Create New...