Mtdave2

Yamae

Why did you check it removing the cap for the reservoir?

dicer

With lower pressure (with no cap on) there could be localized areas that are boiling. I never knew you had the cap off. And it lets the pump easily cavitate too. Put the cap on it. And if the temperature is stabilizing I wouldn't worry about it. Also with no cap there is a chance of constant air entry.

Mtdave2

do you all think that I am driving without a cap? from my understanding, when you are burping the system you take to cap off. the bubbles do exactly the same things with the cap on or off.

The idea of some trapped air is a good one. I will try a few things to help urge them out.

Banshee365

Dicer is correct on the pressure thing. Cooling systems are pressurized partly because it raises the boiling point. A cooling system at zero psi will boil much sooner than a pressurized one. If it were me I would connect a pressure gauge with a good scale between 0-20 psi and Tee it into the small hose going into the upper part of the coolant bottle. Put the gauge under your wiper or something and see if the pressure raises significantly with engine load and rpm while you drive.

If the pressure shoots up under a hard acceleration you have a head gasket issue. If the pressure slightly raises with load and RPM your head gaskets are fine and you need to look elsewhere. I would also watch coolant temp with something like a scan gauge or torque app and see if temp spikes with engine load.

Mtdave2

I did hook up a gauge as you suggested. I am still trying to process what I saw. I took all sorts of videos so I can review.

Here is a video of some revving and the reaction of coolant pressure.


the pressure built to about 15psi once it got the temp up to 140.

This was not while driving, it was in my drive way, i will do a test while driving tomorrow.

Mtdave2

a few things that I do not understand at the moment.

first, I connected the gauge and started the motor. I didn't have much pressure but it built quickly while holding 2000+ rpm. no video of this step. wish i did.
I did the video above, then I just kept on revving watching the temp climb. I wanted to get it to 240 or so just to see what happens. it reached 245 then started cutting the rpm up and down while I held a constant pedal. it could be a fuel thing is guess. hum, I do have a video but it sucks, I flip the phone all over, but I'll post it so you can see the rpm go up and down at the start, then I go verify the temp with a thermal gun. Doesn't help that I had a cigar in my mouth lol.


2nd thing I do not understand. I let the motor cool down at an idle, to see how long it took. it took about 20 minutes to do so. At 195 i had very little pressure, like 3 or 4 pounds, I could squeeze the upper hose. I began to rev it again and the pressures started to build at a steady rate. though it was far lower than the first test. perhaps one of the hose connections started leaking... i will see what I can find

Banshee365

Your coolant got to 240 degrees?

djamps

I read the whole thread and I'm fairly convinced you've got a failing head gasket.

fixmiester

Not sure where to start, but IF your temperature readings are anywhere near accurate, you have a serious problem. An idling, a lightly loaded engine, with normal coolant circulation, should only reach about 200 degrees F. The thermostat should open around 195 degrees, pass coolant into the top of the radiator, return to the engine around 165 degrees, and so on. Only under the absolute WORST conditions (extremely hot ambient, heavy engine load, AC on) will the operating temps reach the 240 degree range. You must have a severe coolant restriction somewhere for temps to be getting that high, which totally explains the bubbles; your engine is a giant percolator.

First remove the thermostat and see if that drops the temps to around 200 degrees, or lower. If not, then you have serious engine block/radiator restrictions. You should be able to run a garden hose wide open into the top of the radiator, and watch it run out through the radiator at full blast with the lower hose disconnected. Then do same test pushing the water through the engine block, with the thermostat removed of course. I suspect this will reveal the problem.

Mtdave2

Well I have done all that you have suggested before, it all seems fine. As far as the blown head gasket, I agree it sure sounds like one. I just can not verify it, I checked again with the block tester, there is no hydrocarbons in the coolant. I even thought that perhaps the detection fluid was defective so I drew in air from the exhaust pipe...it works!

I may may do a compleat drain again, run the garden hose through again to see if there is a restriction, but there was no issues last time. What do know is fluid is not circulating properly, there are bubbles in the system....why?

jaaa

Have you yet pulled the thermostat?

Banshee365

I would be WAY more concerned with 240 degree coolant than bubbles man, big time. You shouldn't be anywhere NEAR that temp. Check your radiator for blockages. How does your heater operate? If at all question your radiator the OE Denso model is available from rock auto for about $85 shipped.

Mtdave2

yes, I have. and actually when I was looking at that area, I realized that If you pull the thermostat, you are not blocking the bypass, so there is coolant that would come from the motor and be piped to the pump, putting it right back in the motor. Did not make any difference, but I learned a lot of things by looking at that area closely.

Mtdave2

obviously the temp is the main issue. I always have to chuckle at comments like this, yes, we all know it should not get that hot, it is the whole reason for this thread.

heater works fine, I cant use an OE radiator because this is motor swap. did you read the thread?