Thermostat

How is a hole in the timing cover related to coolant pressure? I would think it would leak oil, but I don't see a connection with coolant.

That is a pretty old van. If the solution works, fine... It sounded like, to me, that he had a weakened radiator and didnt want to develop full pressure inside it.

I have a 98 Dodge custom van with the 318 engine, and had to loosen the cap on two occasions, (1) when the Welch plugs developed pinholes and (2) when a hose developed a leak. Got me home safely both times.

Of course, all this is simply stopgap until he can fix it, or get home and let it die a well deserved death.

The water pump is mounted on that casting and passages connect to the water pump.

-jim

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I couldn't find my old can of engine degreaser stuff, I guess I threw it away a few months ago.I have a gallon of mineral spirits and a quart can of acetone.I used the acetone and a 3/4 inch wide artist brush.I think I have it clean enough now, but I am going to work on it some more.Tomorrow I will mix up some J B Weld and I will let the J B Weld set for a day or so.When I start the engine I am going to let it sit there and run for about an hour with the radiator cap loose and see what happens before I drive anywhere.I think I will buy a 4 lb radiator cap, somebody mentioned a 4 lbs pressure rated radiator cap.There isn't anything wrong with the radiator, it is the timing chain case cover where the hole is.At least that is what somebody said a few months ago in this newsgroup. cuhulin

Running your engine on low coolant pressure is not good for several reasons. However, if you really need to do this, then you can keep the pressure low for the longest run time and distance by completely removing the thermostat. That will cause the maximum coolant flow and heat dissipation, holding off boil over for longer than *any* thermostat.

Most cars should tolerate this slight abuse fairly well. It's about the same thing as driving a normal engine before it has warmed up, but for a longer time. Most folks do that every time they start their first drive of the day.

At the same time, change your driving habits to minimize engine heating. Drive at higher RPM and lower gear than normal, drive slowly, and don't push the car up long hills. Between driving slow and gearing down, use a light touch on the accelerator as much as possible. Stop and cool down a while if the temperature gage comes up near to normal. Keep your coolant at the right mixture for highest boiling point, which I think is 50% water.

If the car has an electric radiator fan, then switch the control wire from the temp sensor to the ignition circuit or a manual switch, so that the fan runs all the time when the engine is on. This will buy significant extra time before boiling. If your circuit has a fan relay, then swap the relay control wire rather than the fan control wire, because the relay current is much lower.

Altogether these methods should get you a few miles farther before the coolant starts blowing. A low pressure thermostat will not do you much good compared to these other methods, if you have a hole in the cooling system.

Whatever you do, don't ever run dry or to full boil. Both of these will burn up or sieze your engine, starting with the head gasket and worse. Good luck.

--Dave

snipped-for-privacy@webtv.net wrote:

Oops, second to last paragraph, I meant to say "A low pressure RADIATOR CAP will not do you much good...".

--Dave

Dave Allured wrote:

Yesterday about 12:00 PM/high noon, I put some J B Weld on the area.I am letting the van sit a few days before I put some water and antifreeze (Prestone, of course) into the radiator, I am not in a hurry to drive anywhere.There are no real hills around here to speak of.I always stay on the back streets where I can drive slow, my speed, 100 percent city traffic.I am scared of the interstates, those people are crazy out there and my sixty seven years old reflexes aren't what they used to be.The slower I can legally drive, the better I like it.I might remove the thermostat later on and see if that helps.My old van doesn't have an electric radiator fan, it does have a plastic coolant recovery tank mounted near the top area of the radiator. cuhulin

I own a 1914 Ford Model T Runabout Roadster Car.I don't drive it around though.If I did, that brass radiator probally wouldn't be on there after I came out of whatever store.I also own a 1948 Willys Jeep, I paid a guy in a nearby town $300.00 cash for my Jeep.Jeep is completely worn out, it was like that when I bought it, he said it has two burned valves.And I also own a 1961 made in Germany Hercules Moped, it has bicycle pedals on it, Moped only has sixteen original miles on it.I am too fat to get behind the steering wheel of my Jeep,

I am not too fat for my raggity old 1978 Dodge van though.

The no thermostat trick is good for summer. When you start freezing your butt in the winter, might be a good time to put in the lowest rated thermostat you can find that will fit in the hole.

Timing chain cover? That should be dead air space or crankcase air inside, not coolant! If coolant is coming out there, your leak is in a worse place inside the cover! Am I seeing this wrong?

Is your water pump anywhere near this spot??

--Dave

snipped-for-privacy@webtv.net wrote:

Shes too fat,,,,,, sheas too fat,,,,, shes too fat for meeeee,,,,,, cuhulin

No, you arent seeing it wrong. He has been on about this for months. He apparently has a coolant leak somewhere near the front of the engine and found a "rusted out" spot. Hard to say exactly what is causing the leak.

If he wants to take short runs, then removing or loosening a cap is one way to keep the pressure off the liquid (if any) in the cooling system. It is not a fix, for sure, but can buy you some time to get home or to the FLAPS.

Removing the thermostat while leaving a pressure cap in place just forces more coolant out the "hole", which is lower in the system than the filler cap, in this case.

You havent followed a lot of Cuhulin's posts, have you ;>)

The hole isn't due to rust. The casting where his leak is should be aluminum. Rust I believe is corrosion of iron based metals only. The hole is probably the result of a casting defect combined with years of corrosion. He has a round hole that is 1/4" in diameter so he should be able to fix it with a good quality epoxy if he gets the metal good and clean and the metal surrounding the hole is still sturdy. A 15 lbs cooling system will only exert a 1 lb. load on the patch so it should be able to hold that. If it seals without pressure - it should be OK.

-jim

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Ah. Thanks for explaining. There is a thermostat elbow up in that vicinity, isn't there? That and water pump are likely suspects.

Well, I must agree with you about loosening the radiator cap. However thermostat in or out should not make any immediate difference in added pressure at the leak.

The main effect of removing the thermostat is that the engine will run abnormally cool because coolant is circulating at full flow all the time, and removing more heat through the radiator. This extends the drive time before the engine interior heats up to coolant boiling point. When coolant starts boiling and spewing, it is time to pull over and cool down a while.

Hah, you got me on that one. Not lately. Well I do enjoy chatting with the fellow about kludging engines and tobacco and stuff, at least when he is not busy mocking me.

Catchy tune, though. ;-)

--Dave