Air in cooling system

Hi and thanks everybody on this chat, great place for ideas and help. I’ve been having issues bleeding air out of my cooling system of my 328 since I bought it in 2010. I always ended up with a water full header tank and an annoying drip from the header tank overflow. After trying different approaches, the only ones that, seem really to work (and are very simple) are; The first arrangement is, Fill the header tank all the way up(with the heaters fully open), bleed radiator and thermostat housing, top off header tank and install a secondary water reservoir. This secondary reservoir is fed by the overflow hose on the header tank. Reservoir tank only needs about an inch of water. I’ve used this arrangement for three years… No problem, no overheating, no drips, no leaks. The second arrangement (and even easier) is plugging the upper feedback hose on the header tank. This is easily done by removing the hose on the header tank, inserting a plug in the hose (plug has to be tight), and hooking the hose back to the header tank. Bleed the system and fill the header tank coolant level to manufacturer’s specifications. Results are as with first arrangement… No overheating, no leaks, no air in radiator…

Don’t ask me why these arrangements work and the original design doesn’t.

 

Morning, this thread is related to the previous one I posted. Can someone give me an answer or help me out?

The idea of using a coolant reservoir tank is not mine, I copied it from a water cooled VW Vanagon, which basically has the same cooling system layout as the 328. I went this rout because there was no way of bleeding air out of the cooling system. I would always have air in the radiator and the header tank would eventually overflow (after driving for about ten minutes) no matter what I tried. Now I’ll explain what steps I followed in order to solve the problem.

I began trying to find any leaks, so I pressurized the system and pressure would not drop. Apart from that I separately pressure tested the heater coils and the radiator, with no leaks showing. From there I moved on to replacing all the water hoses and rebuilding the water pump. Nothing cured so far… so I figured out it could be a blown head gasket. Took the heads off and took them over to the machine shop. Ran two tests; cracked head test and warp test. Both were negative, never the less I shaved the heads. While the heads were off, cylinder liner height was also checked, all were within specs.

New gaskets and heads torqued to manufacturers specifications… same as at beginning, nothing cured.

Last thing that popped my mind would be a crack in a cylinder liner, now… if that’s the case, why would the coolant level stay stable using the coolant reservoir?

Could it be that the heater coils sit above water level? For now I ran out of ideas.

 

Thanks, I'll do as you recommend, after a leak down test.
Right now the engine has been taken apart due to bearing noise in the timing drive pulleys. Since I had to pull the engine out, I pulled off the heads just to check cylinders and pistons. My surprise was that #5 has severe vertical scratches. All the rest looked and measure ok.
My next step was locating a liner...luckily I found a used one in Italy, 400 Euros plus shipping. Pictures show liner in very good condition.
I'm planning on replacing the liner and new rings for the entire engine. The old rings were on wear limit (0.8mm).
Since these liners are Nikasil, I'm not planning on touching them, just cleaning with alcohol.
I"d appreciate any hints and comments that could help me out.

 

The car didn't need an additional overflow tank when it was new.

 

+1
I feared a head gasket leak on my 85 QV, but after 5 drive/bleed cycles there's no more air in the system and temps are normal. The gauge sticks sometimes (tapping it drops the needle), but better to rebuild the gauge than the engine. BTW, not to hijack, but who do you guys recommend for gauge servicing?

 

Hi, I recall seeing that gauge at Superformance UK. Maybe replacing it is the best solution.

 

That is true. Once I have the engine back together, I'll do a leak down test, hope for no surprises.

 

You could use a vacuum fill system for the coolant. It will help to bleed the system. I had a Dodge truck I could not get the "gurgles " out of unless I vacuum filled the system. Basically you pull a vacuum on the cooling system and it will suck the air bubbles out and replace it with coolant. Its not so important at the beginning but it can help chase out those last bubbles of air trapped up nook and crannies. Its vapor lock with cooling Water doesn't compress or expand very well so pulling a vacuum will help chase out air pockets.

 

Thanks! Let's see if I got it right...First, fill it up with coolant, second bleed and third vacuum the system through the header tank. Is this correct?

 

VERY NICE PAUL

 

Kcabpilot, I wanted to thank you for this thread. I own a 1985 308 GTB QV that I purchased in November of 2006 with 85’000 miles.
I had cooling issues soon as I started driving. It started with a blown radiator hose, overflowing coolant tank, more blown hoses and eventually constant bleeding of the radiator tank. It was driving me crazy. Until one day, last Feb. I stumbled on your thread. Everything you went through, I went through. The more I read the more I knew I had the exact same problem as well. Leaking head gasket. I went back to my compression test and sure enough cylinder 5 and 8 had 120 psi and 119 psi respectively. The odometer is at 99’700 and my car is now in the safe hands of Dave Helms and his crew at Scuderia Rampante (I am by no means as skilled a you are mechanically).
Thank you again for your very helpful thread. Image Unavailable, Please Login

 

With the mid engine setup, it helps if you put the front wheels on blocks and then jack the rear up really high- the 430 is hard to bleed and one of the threads on 430 shows this way as useful.

 

Since the car bleeds at the front radiator, how does raising the back of the car benefit? (As air doesn't travel down.) Maybe I'm missing something, feel free to expound.

 

You actually should do the reverse and try to have the nose of the car uphill, to open the bleed screw....