Best way to diagnose overheating issue?

[e30onBBSs]

I finally got my e30 running with no problems besides my overheating issue. I replaced the thermostat and I just did the timing belt and water pump. My car had no fan when I bought it and I got a brand new fan clutch and fan. When I drive it it slowly creeps up like a normal car does, then it stays at 1/2 for enough time to give me hope then it goes towards the red. I really don't think it's a blown head gasket, there is no stuff under the oil cap and the exhaust is fine. Could my gauge be lying? I bled the system with the thermostat "drill a hole" way, and when I turned the car off I could hear bubbles coming from the radiator, which seems like a good sign. My heat doesn't work. The water pump/alternator belt is a bit loose but it spins fine. A friend in France gave me a new expansion tank cap as well. Any ideas?

I've been doing lots of research and many times it's been people's radiators. They said to get an infrared thermometer and scan the radiator for cold spots. Is this a good investment?

One time my car over heated pretty bad, but I have no tell-tale signs of a blown HG. It was left at idle as I was trying to get a sticker and then it was like shit it's smoking coolant. Should I test the coolant? Would there also be driveability issues with a blown HG? It runs like a champ and idles great and healthy besides this overheating problem. Would there be misfires or something?

[e30onBBSs]

Best way to diagnose overheating issue?

In the Bentley it says to check the aux fan, was there an aux fan on a 1989 325i from the factory?

Upper rad hose is hot at temp, a couple hoses were leaking so there may not be adequate pressure on the system and when I opened the bleed screw coolant and bubbles came out.

I am also missing a fan shroud. How important is a fan shroud to direct the air?

[jeffnhiscars]

They all had auxiliary fans but they really are just for when The ac is running or if the engine gets very hot so the absence of one would not cause it to overheat. I'd also say bubbles in the radiator is a sure sign of a bad HG and, if confirmed is the most likely source of your problem.

[e30onBBSs]

They all had auxiliary fans but they really are just for when The ac is running or if the engine gets very hot so the absence of one would not cause it to overheat. I'd also say bubbles in the radiator is a sure sign of a bad HG and, if confirmed is the most likely source of your problem.

A friend came and helped today and we couldn't nail the issue but we discovered that a lot of the cooling hoses are full of air instead of coolant. I have been filling it from the upper rad hose, then squeezing the hose that connects to the one outlet side of the thermo housing, and I can hear it burp, hopefully the HG is fine. I also am missing a fan shroud which is necessary too. If I get a shroud, fill everything up, and it still overheats then it's probably the HG which would be really bad.

I have a few more questions. Would a blown HG significantly lower the coolant level? Would it be possible to follow a drip to a point where the HG is?

The thermostat opened at 3/4. Is this late?

[jeffnhiscars]

A friend came and helped today and we couldn't nail the issue but we discovered that a lot of the cooling hoses are full of air instead of coolant. I have been filling it from the upper rad hose, then squeezing the hose that connects to the one outlet side of the thermo housing, and I can hear it burp, hopefully the HG is fine. I also am missing a fan shroud which is necessary too. If I get a shroud, fill everything up, and it still overheats then it's probably the HG which would be really bad.

I have a few more questions. Would a blown HG significantly lower the coolant level? Would it be possible to follow a drip to a point where the HG is?

The thermostat opened at 3/4. Is this late?

Don't rule out a wonky tsat. As for the HG if you are getting exhaust in the radiator I believe it can push coolant out the overflow even if it doesnt boil. You could also be pushing it out the exhaust. watch for white smoke ie vapor as that's a pretty good sign coolant is getting in to your combustion chambers

[e30onBBSs]

Don't rule out a wonky tsat. As for the HG if you are getting exhaust in the radiator I believe it can push coolant out the overflow even if it doesnt boil. You could also be pushing it out the exhaust. watch for white smoke ie vapor as that's a pretty good sign coolant is getting in to your combustion chambers

Damn that was happening earlier with the overflow.. I have no exhaust woes though or milky oil. It seemed more like there was air or something trapped in the coolant that was desperate to leave. I hope so! A bad HG would discolor the coolant as well right?

Thanks for the responses Jeffnhiscars! I will keep this thread updated. My next plan of action is to go for a drive and if it still overheats reasonably quickly I'm going to flush the system and fill it hose by hose in a logical order and get a new tstat. This whole problem is wonky because before I did the timing belt or anything it would be completely fine while driving. I never had to worry about it overheating unless at idle until I started messing with the coolant system.

[jeffnhiscars]

There's a test kit you can get that will tell you mif there is exhaust leaking in to the coolant and instead of playing with the hoses why don't yo search for the bleed procedure and do it the time tested way

[Seawolf]

There's a test kit you can get....

^^^This

You can also run a compression test that may indicate HG problems.

If the problem persists you might want to flush / back flush the heater core in situ and pull the radiator for the same.

I usually put the front of the car up on ramps when bleeding coolant system to float the air out of the heater core.

I'd run the coolant gas test first though, the best kit I've found is this and costs about the same as just a pack of Ph test strips: http://www.blockchek.com/

[dnguyen1963]

They all had auxiliary fans but they really are just for when The ac is running or if the engine gets very hot so the absence of one would not cause it to overheat. I'd also say bubbles in the radiator is a sure sign of a bad HG and, if confirmed is the most likely source of your problem.

Unless you did not bleed the system properly, there is no way for air to enter the system beside a leaky HG or water pump.

[330SMG]

Unless you did not bleed the system properly, there is no way for air to enter the system beside a leaky HG or water pump.

+1 on bleeding system. It is amazing what a little bit of air in the system will do. You said you had leaking hoses, those make the level go down and suck in air. Do a pressure test on sytem at 16lbs and see if you have a leak. Not all problems need to be worst case.

[e30onBBSs]

Hey guys thanks for all the tips again. The problem is solved!

A guy who was selling e30 parts in my town came and helped me out. I thought I bled it well, because I did the thermostat hole, then pump it until it flows through the bleed screw, then tighten the bleed screw, and keep pumping until it reaches the overflow. It seemed to work, because most of the time it was burping air at the expansion tank, and it took a lot of coolant.

The craigslist guy's name is Parker and one of the first things he did was feel the upper rad hose, and I assumed it had coolant the whole time, but it was just air. He suggested we undo the side of the upper rad hose that attaches to the thermo housing, and we filled it up into the upper rad hose, then put it back onto the thermo housing when it couldn't take anymore. We kept bringing it up to temp, and slowly it kept creeping up past 1/2. Then we jacked it up and tried the same thing with a different hose, and had the same outcome. It was still overheating, and the hoses didn't seem to fill. We were both stumped and he left because we didn't know what else to try.

After it cooled down, I felt the upper rad hose again, and it still felt empty. When I took it off the thermo housing, the thermo housing was empty too. It was time to start trying something new, so I took the upper rad hose off, and poured in coolant/distilled water. I then started squeezing random hoses, and squeezing them with the expansion tank open would lower the coolant level in the upper rad hose, and cause bubbles in the expansion tank. This was a great sound, and a great break through because the upper rad hose kept taking coolant as long as I kept squeezing the hoses. The main hose I squeezed was the hose on the right side of the thermo housing, it is the one that connects to outlet that bolts to the real thermostat housing with three bolts. I kept pouring and squeezing until it would overflow out of the outlet that the upper rad hose connects to on the thermo housing. Then I took it for a drive, and it went a bit more than twice without creeping past half~ 2.5km. My neighborhood is about a kilometer circle with some cul-de-sacs, and I did two laps and one cul-de-sac. I got home, as she was at about 3/4, shut her down and waited until she was cool. A couple hours later, I took off the upper rad hose from the housing and there was coolant in the thermo housing but again, the rad hose was completely dry. I did the same process as before, and this time it didn't take nearly as long until the upper rad hose and the thermo housing were full of coolant. I left a couple inches of the upper rad hose empty so when I had to put it back onto the outlet it wouldn't spill everywhere.

I did this filling as it was getting dark, and I had to clean up my tools and what not so I was like ok I will wait until tomorrow. I got up this morning and drove it about 6 miles and it was a tad below 1/2 and stayed that way from about mile 1.5 on. It was so awesome when that needle stopped, where it normally keeps going!!

Thank you guys for giving me ideas and just being able to read some responses really helps channel my thoughts and get new perspectives. You guys are the best!

the tstat is a few degrees below stock, but for now it's great compared to what I had been dealing with. :)

[jeffnhiscars]

Glad you finally got this resolved. What has me scratching my head is that for all the bleed fail threads I've read I have never once ever had an issue. I must have drained and refilled various cars a total of 25-30x (at least) and have never jacked a car up, stood on my head or on one leg. I just make sure theres a bleed hole in the Tstat and that the heater temp control is set to hot.

Then again I've also never had any issues getting.a fan clutch to unscrew. Must be just lucky :)

[dnguyen1963]

Knock on wood, Jeff.

[e30onBBSs]

Glad you finally got this resolved. What has me scratching my head is that for all the bleed fail threads I've read I have never once ever had an issue. I must have drained and refilled various cars a total of 25-30x (at least) and have never jacked a car up, stood on my head or on one leg. I just make sure theres a bleed hole in the Tstat and that the heater temp control is set to hot.

Then again I've also never had any issues getting.a fan clutch to unscrew. Must be just lucky :)

My heat is basically non op so that didn't help! Now that I've been done it right I hope I won't ever have to do it more than once next time.

And here's a good tip if you want to reuse your coolant. I picked it up from a biology lab. We had to filter something from a liquid, and this is that on a bigger scale. Especially if your car is outside like mine, where random little bits and pieces get in the catch pan. Get a big funnel, and cover the funnel with a towel. Not a paper towl, a real towel. Pour your coolant in and go work on your car while it's seeping through the towel, leaving all the debris behind! Saved me lots of $ in coolant from not tightining the water pump bolts enough and what not