Cooling system woes

[cscracker]

BMW blue is ideal, but the regular green stuff will do. That said, some coolant manufacturers color non-standard stuff green. Just make sure it's normal "conventional antifreeze", ethylene glycol, not dexcool or any specialized type.

[shawmcbigdis]

Always good to see a happy ending. Just an FYI that you want a coolant that is phosphate free.

The orange ones like Dexcool have the phosphates right? This is good old green stuff, but I will double check the bottle to make sure.

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[jeffnhiscars]

Always good to see a happy ending. Just an FYI that you want a coolant that is phosphate free.

[e30davie]

It's always the simplest things.

Now you will never put a thermostat in without first checking it.

[shawmcbigdis]

So go back from vacation last night. Drained the whole system, pulled the tstat and stuck it in hot water on the stove.

To my shock, it never opened, bad thermostat! Brand new Wahler from Bav Auto. I never would have guessed that would be the issue, but I guess anything can happen.

So off to Autozone, got a new t-stat,some cooling system flush and a bunch of new premix (because I'm lazy). Filled it up with the flush and hose water, ran it for about 20 mins, it did get pretty warm but I didn't bleed it at all, so to be expected. This morning, I drained all that I refilled with 50/50 mix. started it up and bled the system, and it's totally fine. After 40 mins of idling it got up to just barely past the 3rd tik on the gauge. Driving around it just sticks in the middle. Was super easy to bleed. Amazing how much a working thermostat helps.

Thanks for all the help guys, it honestly would have taken me forever to get to the point of checking the tstat because I just wouldn't think something that simple would be DOA.

On to the next project!

[shawmcbigdis]

Done this yet?

Not yet, did t have a chance. And now I'm gone for a week.

When I get back I am going to do this. If it is working properly, I will empty the whole system again, flush the rad and refill. I will try finishing it off this time with a op through the overflow hose to try and minimize the air getting in while filling.

Hopefully all that fixes the issue.

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[wilholl]

If the little bleed hose at the top of the radiator is plugged, it will cause all of this nonsense to happen...


from experience!

[e30davie]

Put the thermostat in a pot of water and chuck it on the stove. Watch it open as the water heats up and watch it close as the water cools down.

Done this yet?

[dnguyen1963]

So I just realized something. While the car is running, the upper radiator hose should be pressurized and pretty firm, correct? The hose never gets hard, like its empty, no fluid no pressure.

Am I wrong in that assumption? So does that mean there is such a big bubble in the system the water pump isn't functioning properly? If that's the case I would assume I should empty the whole system and refill from scratch to try and get a better fill. Correct?

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This is not a good sign. The upper radiator hose should be full of fluid when the t-stat is open. If not, then your t-stat is not functioning properly or your water pump is not pushing any fluid through the system. I would flush all the hoses and the radiator (a clogged radiator could be the source of your trouble here) to make sure that there is no clog anywhere.

[shawmcbigdis]

So I just realized something. While the car is running, the upper radiator hose should be pressurized and pretty firm, correct? The hose never gets hard, like its empty, no fluid no pressure.

Am I wrong in that assumption? So does that mean there is such a big bubble in the system the water pump isn't functioning properly? If that's the case I would assume I should empty the whole system and refill from scratch to try and get a better fill. Correct?

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[shawmcbigdis]

You forgot one of the most important things, the gauge cluster. The E30 gauge cluster is extremely common to read too high. This is due to oxidized gauge connectors, loose grounding and failing SI board which controls the gauge.

Until the SI board and cluster are refurbished, you cannot trust a 30 year old failing cluster.

I just replaced the side board batteries and cleaned the ground screws last week. And it was fine before I worked on it. Now all I did was the test drive, then drive it the 100 miles home, and maybe 2 little drives around the neighborhood before I replaced everything, but it was all fine then. Afterwards all hot.

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[Gregs///M]

You forgot one of the most important things, the gauge cluster. The E30 gauge cluster is extremely common to read too high. This is due to oxidized gauge connectors, loose grounding and failing SI board which controls the gauge.

Until the SI board and cluster are refurbished, you cannot trust a 30 year old failing cluster.

[shawmcbigdis]

I do believe they will fit in backwards, you can remove it and just reinstall the O ring and being able to fill a radiator doesn't mean it's not partially clogged. Hit it with an iR gun to see if it's even temp everywhere.

You've got lots,of small passages that can greatly reduced cooling capacity. The radiator is actually part of a 100k total cooling system update and the hand ful I've replaced have all made a difference, even on cars that did not overheat.

OK, I just double checked every pic, video and diagram I could find online, and I do have the t-stat installed the right direction. Honestly at this point I was hoping I didn't since that would be an easy fix.

You are right in that I wasn't thinking about the radiator right, it could still have lots of clogged tubes, thus greatly reducing it's efficiency. Although I would think that if anything was going through it the lower hose running to the t-stat would still get warm, actually downright hot if it's not cooling well. But that hose barely warms up at all.

Well like I said, I won't be able to touch it for over a week. So hopefully then I can figure it out.

[jeffnhiscars]

Is it at all possible that you have installed the T-stat backwards? You would definitely be overheating if that's the case. Something to consider and eliminate.

I do believe they will fit in backwards, you can remove it and just reinstall the O ring and being able to fill a radiator doesn't mean it's not partially clogged. Hit it with an iR gun to see if it's even temp everywhere.

You've got lots,of small passages that can greatly reduced cooling capacity. The radiator is actually part of a 100k total cooling system update and the hand ful I've replaced have all made a difference, even on cars that did not overheat.

[jgilber0]

Is it at all possible that you have installed the T-stat backwards? You would definitely be overheating if that's the case. Something to consider and eliminate.