Tishabet

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

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Yup, had that mentioned to me as well. Never realized what purpose that kind of thing serves....you want, ideally, heat at your heatercore before the thermostat opens....that would be an awful long time before the cabin would unfreeze you in the dead of winter! So that lets it flow through the heater hoses as well. Buuuuut once the stat opens, that doesn't matter anymore. Should it be ignored, NO, why do something halfway? However, that won't cause an overheating problem, assuming the thermostat works.

And if it hasn't been mentioned yet, get a 160 degree stat, that is actually the correct stock one anyway if you look at a shop manual, but nevertheless. I'm pretty sure the NAPA by me was kind and knowledgeable enough to just take a measurement I had and find a 160 stat that fit there, seeing as there was no listing for a '38 Buick stat. At the time anyway. And PLEASE don't get one by Mr. Gasket. At least get a Stant "Super-stat" they're a few dollars more and probably more sturdy. That's about all that's out there but I've had friends tell me they bought basic Stant ones that got stuck after not too long. Oh well. At least it's real easy to get to on these engines! :D:D

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Hey guys,

work has been insane lately but I finally got a couple of hours of work in tonight and thought I would give you an update. I'm assuming from my testing that the condenser was the cause of my breakdown issue, so now I am concentrating on the cooling issues.

First thing I did was start up the car, then warm it up a bit and checked the temps on the radiator with an IR thermometer. I did not get the engine all the way warmed up because I was going to work on it, but mostly wanted to assure myself that the radiator didn't have any cold spots... it did not, and the temps were 25-30 degrees cooler at the bottom than the top once the top was up to 150 or so.

Next thing I did was add about 2 cups of "simple green" (a general cleaner) to to water in the radiator and circulated it for 30 seconds or so, then shut down the engine. I then did other stuff to the car for an hour while the engine cooled and the simple green soaked in.

Next I disconnected the top hose from the pump and ran the engine while I filled the top of the radiator with a hose in order to flush the system. Nothing significant came out in terms of crud, and I ran it this was for about 10 minutes to make sure the engine was good and flushed. I have attached a pic of the flow from the pump at fast idle (idle with idle cam turned up), does it look OK to you guys? No wobble could be felt in the bearing, but I did not remove the pump to look at the impeller.

I did verify that the thermostat is functioning, but replaced it with a new 160 unit from Bob's anyway as mine appears to be a genuine antique... I've attached a pic for your amusement, unit was marked "GM."

Next I popped out the freeze plug closest to the firewall under the manifolds and took a look inside... looks very clean to me (pic attached), so I did not pop the other plugs. I felt around inside and found a bit of "sand" in the very bottom of the jacket, so I hooked the hose up to the top of the radiator and turned it on... water really gushed out of the freeze plug hole, so I'm feeling pretty good about the flow through the radiator and the block. I installed a new plug from Bob's and called it a night.

So I'm concluding that the radiator is flowing/cooling well, the block certainly appears clean and the pump seems to be working pretty well (though I'm interested in your feedback on my pic of the pump at fast idle). I've flushed everything for good measure and have a new thermostat, but don't expect much difference from those steps.

How do I verify function of the "other" thermostat for the heater? I can see it down the barrel of the pump when I remove the thermostat and it looks clean, but I'd like to eliminate it as a possible issue.

Finally, I think I will probably advance the timing a bit... it's currently set to factory spec but I have heard that I can advance it a bit with modern fuel to achieve cooler running. I'll let you guys know what I find out!

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Edited by Tishabet (see edit history)

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You could rip your water pump off and have a look. I had the water pump off the 38 I'm using as a daily driver the other weekend. Checked out the re-circulation valve while I was there. Might pay to do the same? You could even check your impellor while you're there!

Cheers

Grant:)

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Yes, I think it might be worth pulling the pump off just for a look-see. How can I "check out" the recirculation valve, i.e. do I just make sure it looks crud-free and moves freely and assume all is well?

For that matter, I cannot imagine I will be driving the car in cold temps and have in fact plugged the inlet/outlet for the heater at the pump. If I have the pump off, can I just remove the "other" thermostat entirely and call it a day, or is that asking for trouble?

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That pump flow looks very weak to me, however if the thermostat was fitted at the time and without knowing the internal flow route, it could be the thermostat was passing some flow internally.

Nevertheless considering that you have done everything else why not remove the pump and have a look ?

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The water bypass valve in our 38 was in quite good condition. It's spring loaded, and you can clean it up and push down on it to see if it's free. The concensus amongst the guys here is that it's an important component in the cooling system, and needs to be there (from the thread where our 39 coupe was overheating). I take it that you've tested your thermostat in hot water? I had a dud thermostat in my 39 Chevy that gave me grief.

Cheers

Grant

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OK guys, I will definitely pull the pump and check this water bypass valve to see if it looks OK. I did check the new thermostat in some water on my stove, and the old one seemed to work based on my flush... water was kind of dribbling out while engine warmed, then suddenly turned into a gusher.

For the impeller... I just want to make sure it looks clean and is not obviously corroded, correct?

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Hi guys,

I pulled the pump to take a look. The bearing seems A-OK.... no wobble or movement, no clicking, very solid. The bypass valve appears very clean and everything moves freely, the rubber sections appear fairly new and are not cracking.

I've attached two pics of the impeller... it is not corroded or rusty so far as I can tell, but does have a fair amount of "scummy" buildup that I can scrape off with my fingernail. I've tried to show it as well as I can.. the second pic shows the buildup pretty well.

Between the pics of the impeller and the pics of the flow out of the pump, should I be able to conclude that the pump is OK? If so, I guess it is time to re-assemble everything, advance the spark a bit past factory, and hope for the best?

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Hi Grant.

The water pump bearing will roar when it's on the way out. And if it's seal isn't leaking, you're all good.

The water looks like it's flowing ok as well.

So, have you taken the draincock out of the block to see if water flows?

Timing?

Not too lean mixture?

Radiator not blocked?

Thermostat opening early enough?

Lower hose not constricting?

Diverter valve in place?

Not losing water? ie head gasket ok?

I know most of that stuff's been covered, but I thought I'd sum it up.

Actually, the Aussies on the forum would be interested to know that in the weekend, the water pump died on my EA Ford Fairmont. Which lead to the head gasket blowing, an EA trademark! Might look at an AU head gasket. I hear they're better.

Cheers

Grant

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OK pump looks good, however I still think there should be a greater flow from the pump than what you are showing; very difficult to establish what is correct without a known flow rate on the pump. The fact that you are pouring cold water from the tap into the radiator could mean that the thermostat has closed and we are only seeing bypass flow.

From what we see the block looks good and all other factors have been covered, so we come full circle back to the radiator, maybe to completely eliminate it you need to have it professionally cleaned out ??

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