37 MODEL 47 running hot

Well I made my first road trip and she overheated, so I'm trying a new thermostat first.

I was running 50- 60 mph the temp would be fine but a little hot 185-195 according to the gauge for 30 minutes or so then start to rise.

even during short runs less than 10 mi. when i turned the engine off I will have a good amount of coolant come out the over flow tube.

second question what is the purpose of the bypass valve

mark

Hi,

The unintended purpose of the bypass valve is to overheat the engine when it fails. :-(

--Tom

There are about 100 reasons why one of these Buicks will run hot. An engine in good shape will not overheat.

You'll have to give more history to get ideas (and there are plenty!) on how to cure your problem.

The purpose of the bypass valve is to let the water circulate when the thermostat is closed. Once the thermostat opens, the bypass will close.

I'd check your old thermostat by putting it in a pot of water and slowly heat the water to see it the thermostat opens. If it does a new thermostat wont cure your problem.

Thermostat failure is pretty rare. Sure it happens, but on these engines it is usually a problem with heat transfer due to crud in the engine or radiator.

Don

Mark:

You can also try just removing the thermostat altogether and take it out on the road. If the temp goes above 180 deg you have issues.

But I can say with about 90% assurance that it is radiator or rad and block combo. When I got my car I had the same issues and that's what everybody told me on here. But I can be a stubborn so-and-so and pulling the radiators on the pre-1941 cars is a pain and recoring is expensive. So if you are stubborn like me you will go down that river in Egypt and try chemical warfare and pulling a freeze plug or 2 and cleaning out the block, but the problem will likely remain until you bite the bullet and yank the radiator. So save yourself time and frustration and just go ahead and attack the radiator first. You will be glad you did!

Cheers, Dave

Does that engine use an internal water distribution tube, like the Oldsmobiles did? They are notorious for rotting out and causing overheating issues.

The very first thing to check is the bottom hose. See if it collapses when your rev the engine....or just replace it with one that has a spiral support spring in it.

here is a update and a bit of history, prior to the O/H problem I thought I had a radiator leak at the lower elbow, romoved the rad. had it boiled no leaks bad lower hose. At that time i put new hoses on it. Today I found in the box of parts that came with the car an original style (long bellows) themostat, I installed it and took her for a drive, under 55 does not go above 180 55 to 60 it keeps on rising, back to 45-50 temp goes back down to 180. the car has 29000 original miles on it. So in my opinion that leaves two things, impeller on water pump or build up in the block. When I had the water pump off during the radiator check I only checked for loose shaft, it was good so I put it on.

Question 1 is the impeller cast iron are the prone to deterioation?

here is the darn it of the whole deal, a new water pump came with the car, I did not find it until the radiator job was done.

I have owned ths car 4 months, so i have not had a lot of personal history with her.

question 2. I have been running 93 octane alcohol free gas, can I run 87 octane 10% alcohol gas. It's a low compression engine so 87 octane should be fine, I'm not sure about the alcohol.

thanks for your advice so far.

one more thing, when it was at about 200 degrees I pulled over and reved the engine to see if the lower hose collapsed, it did not.

Well I made my first road trip and she overheated, so I'm trying a new thermostat first.

I was running 50- 60 mph the temp would be fine but a little hot 185-195 according to the gauge for 30 minutes or so then start to rise.

even during short runs less than 10 mi. when i turned the engine off I will have a good amount of coolant come out the over flow tube.

second question what is the purpose of the bypass valve

mark

The pump impeller is cast iron and, while possible, is unlikely to be bad.

You dont need 91 octane in an engine with a compression ratio of about 6.5:1. The lowest octane is better than anything it ever saw when new.

Again, did you check the thermostat for correct operation?

Boiling a radiator is no guarantee that it will actually be clean. It should be rodded (top taken off and rods run down the tubes) to be sure it is OK. Finding a shop willing to do this today might be a problem. It was common in the old days.

While a really low mileage car, if it sat for years with just water in in the cooling system, the bottom of the block could really be a mess. While not a fun job, knocking out the "freeze" plugs and checking the bottom of the block cooling passages would be a good idea.

Don

I don't believe the car sat and certainly not with antifreeze it spent it's entire life in Wisconsin prior to me buying it. I'm the 3rd owner thee previous owner had it for 30 yrs. the first owner had it painted and bumpers chromed. so it seems to have been actively cared for but not5 drove much

I just checked the themostat I pulled out it opened at 170 full open at 180 back closed 170

I'll get a 160 degree in the AM tomorrow and try that

Mark, I agree with the others. You are wasting your time, if you do not at least pull the radiator and have it rodded. A new core is best. I have been around cars almost as long as yours has been around.I have seen, and I have tried every band aid approach there is. Bite the bullet and repair, replace the radiator now. You WILL eventually.

Ben

For me, even recoring the radiator didn't solve the problem. I had a huge buildup of crud in the water jacket of the back two cylinders. I pulled the head and used anything I could to get in there and pick at the crud. Rinse, pick, rinse, pick.... Runs as cool as a cuke now, but I had to do the needful (as our Indian friends would say).

I restored my '38 Roadmaster about 30 years ago. I too, had the radiator rodded and I knocked the freeze plugs out of the engine. Poking around and flushing, like Pete O says, I scraped out 1/2 five gallon bucket of rust and crud.

In all these years and all kinds of driving and in hot weather, I have never had it run hotter than the 160° of the thermostat.

Lots of work - worth the trouble.

Hi,

Ditto on my 40 LaSalle. It strikes me that if there are radiator problems, some prior owner probably dumped in a carload of Stop-Leak. That stuff sets up like cement in the water jackets. I chipped mine clear with an air chisel and constant hose-flow of water. I also re-cored the radiator, of course, like the prior dummy should have done.

--Tom

Just to add my 2cents worth here, I too would say the radiator needs to have the tubes rodded.

Boiling the radiator and using all those fancy expensive additives is just throwing good money after bad.

When the radiator is in good condition it has a fair reserve in it.

If the radiator is good, when situations arise that generates more heat (sustained speed or low speed traffic) The radiator just deals with it and is never noticed.

Once that reserve is gone (tubes partially blocked) it doesn't take much to run hot. My experience has been that these things never get better, only worse.

Danny

Mark,

What you describe is exactly the same symptoms I had with my 1937 Century immediately after the restoration was completed. The problem I had (and I think it's actually pretty common) is that the water pump was producing enough pressure that it was forcing the coolant bypass valve open at high RPM. When the valve was being forced open, coolant recirculates in the block instead of going through the radiator. As lower RPM, the valve stays closed and coolant goes through the radiator as intended. I have written up a full procedure on this fix, with images, as this was a rather difficult item to properly diagnose. Please send me a private email to kanas<at>qadas.com and I will send it to you.

kanasqadas.com doesn't seem to work for email or website. Would like to send PM for the fix.

I sent you a PM with my email address

thanks in advance

Mark,

What you describe is exactly the same symptoms I had with my 1937 Century immediately after the restoration was completed. The problem I had (and I think it's actually pretty common) is that the water pump was producing enough pressure that it was forcing the coolant bypass valve open at high RPM. When the valve was being forced open, coolant recirculates in the block instead of going through the radiator. As lower RPM, the valve stays closed and coolant goes through the radiator as intended. I have written up a full procedure on this fix, with images, as this was a rather difficult item to properly diagnose. Please send me a private email to kanas<AT>qadas.com and I will send it to you.

kanasqadas.com doesn't seem to work for email or website. Would like to send PM for the fix.

I received your message. For whatever reason, the "@" in my reply didn't come through. I'm at kanas@qadas.com. I'll send you the procedure per your request.

Running hot update,

this was the fix!!!

Mark,

What you describe is exactly the same symptoms I had with my 1937 Century immediately after the restoration was completed. The problem I had (and I think it's actually pretty common) is that the water pump was producing enough pressure that it was forcing the coolant bypass valve open at high RPM. When the valve was being forced open, coolant recirculates in the block instead of going through the radiator. As lower RPM, the valve stays closed and coolant goes through the radiator as intended. I have written up a full procedure on this fix, with images, as this was a rather difficult item to properly diagnose. Please send me a private email to kanas<AT>qadas.com and I will send it to you.

here's an update!!! NEWS FLASH, run 20 degrees cooler with non-ethanol gas, (it was news to me at least)

I made a 60mile trip to a show this last weekend, my fuel tank had 87 octane 10% ethanol the car ran 180 to 200 degrees. On my return trip I topped off with 11gallons of 93 octane non ethanol she ran 170 to 180 degrees. a little google search and sure enough 10% ethanol fuel burns a lot hooter!! As alcohol burns it produces water vapor resulting in a lean burn. The fuel does burn cooler and produces less btu