SO My dad bought a 90 Turbo 2 the other day. Body is in great condition, no smoke, no overheating. Upon start up we were messing around and I left the rad cap off. I noticed a very small amount of bublles coming out. Not champagne style but one here and there. Any way we let it cool down and start it again the same way. Guess what? No bubbles. I watched that coolant neck for 10 min straight and not one bubble came out?
I was thinking oh **** coolant seals but nope. Car warmed up to 175 and stayed put. Im thinking it has a leaky coolant hose somewhere allowing air in and thus i burped the system? Im confused as all hell.

 

Factory radiator or some aftermarket cheapo replacement? Is the thermostat neck factory

 

All factory S5 stuff. The coolant neck is a mcuhined aluminum piece from rotary works.

 

I bet the plastic end pieces of the radiator are leaking. I would actually start, if I where you, looking toward the top plastic end cap near the upper radiator hose.

Actually, the best thing to do is just say **** it and get a new rad for the car, rather it be el cheapo brass/copper replacement or koyo.

Me, personally, my rad upper cracked but it was such a tiny crack, no coolant leaked but air got sucked in. I repaired it (stupid STUPID idea) and when it failed, it took my front iron and engine with it.

3 cracks in the front iron on my engine.

 

Funny you cite that spot. A few months back I had coolant on my 7's Elctric fan right underneath the rad hose. I was wondering the whole time how did that get there LOL. I have a gd lock on a fluidyne he may buy all while praying its not a seal. Then again if it was a seal bublles wouldnt stp then start like that.

 

If it was a seal it would be continuous. Junk that rad and get something better.

Actually, lol, the best way to diagnose the rad on these cars is...

If the plastic end caps on your rad look like the plastic on your rear view mirror, REPLACE NOW!

 

LOL the old faint muiltple hairline cracks lol When will your 7 be up agian?

 

Went out and worked on it while he was asleep. Seems that the bubbles are back. Before I started it while it was cold I cranked it over with the egi fuse pulled. Using a go pro attached to hood faced directly at the neck I saw no bubbles coming out the neck while I was cranking.
Weird. No coolant smell, no smoke other then two stroke from the premix. Temp sat right 185. Never budged. I think somehow air is getting back in there somehow. I'm stumped.

I even got a clear bottle and used that as my overflow after replacing my cap. Bottle was half full of water. After submerging the over flow tube, no bubbles came out of the tube into the bottle. What. In. The. *****.

 

That was years ago, she is up and running.

 

I bought an 87 t2 back in April. Same thing as happened to my car, it only got worse over time. Lasted a few months and seal finally blew a couple weeks ago. I assume it sat for 20+ years in storage with coolant in it.... Only 60k on the odometer. Got it halfway out, gonna have banzai rebuild it.

Use a coolant pressure tester or a compression check for most accurate knowledge of seal failure. Good luck

 

Agreed on the pressure tester. Cheap from ebay or wherever:

http://www.ebay.com/itm/Mityvac-MV4560-Cooling-System-Pressure-Test-Kit-/120920133542?hash=item1c2766cfa6&item=120920133542&pt=Motors_Automotive_Tools&vxp=mtr

I had a phantom leak at the gasket under the T-stat neck that attaches to the pump housing. Ever so slightly sucking in air. It would once in a blue moon gallop on me and took that kit to find.

 

Went to rent one at Oreillys and it was broke. ****. Gonna make my own. I have one of those little electric air pumps at home.

 

Hmmm discovered a fresh wet sticky spot on the turbo cooling inlet. Aftermarket turbo is oil and water cooled. Small leak looks like on the threaded part.