onevette01

Help, I have a 1990 6speed with 97000 miles on it. My problem is I am losing coolant at least a quart every time driving. First of I pressure tested the system and found no leaks and maintained the pressure for over a half hour the needle never moved. The car also has a brand new radiator,thermastat, and a new 16lbs radiator cap. The oil level is perfect and so clean and the level is the same for the last 3 months. Next I drove the car hard today up to 135 downshifting hard with my son following and he said there wasnt any smoke at all comming out of the car. Pulled the oil fill cap on the valve cover no milky residue inside of the cap it was clean. next I pulled the plate on the tpi and under that there was a little milky residue under the tpi plate there is a hose from the pass side valve cover to the tpi upper. I am at a loss what else can I check and where is it going. Thanks for all you help and save the wave. Rj

Rich Silvestris

Do you have coolant in the overflow reservoir? Are you including the level in the overflow in your loss? The coolant in the system expands as it heats up and squirts past the cap into the overflow, but it won't return on cooling unless the level in the overflow is high enough to cover the inlet tube. It sounds like you know your stuff, but you don't mention this point.

onevette01

The overflow tank was my thought also but I have been watching that too marking the tank and the tank is full I leave the level at the hot line.

onevette01

Can someone help me with this problem I see many question with10 -30 pieces of advice can someone help me. thanks again Rj

65coop

Puddles, smells?

C10 JDR

So, where are you losing coolant from - radiator? - overflow tank?

No don't mean that - I mean where are you measuring the loss from?

ittlfly

It sounds like you have covered about everything. At this point I would do 3 things. Do a cyl leak down test and a compression test to check the head gasket.
Get some of the coolant dye that you add to the fluid. Using a black light after you run it up to operating temps will show any external leaks that may be boiling off when in contact with a hot block. You can get the kit at Napa or have it done by a radiator shop.

onevette01

There isnt any puddles anywhere on the ground. The low coolant light comes on. The level in the overflow tank runs down that is how I am guaging the loss of coolant. The car dosent run hot or has ever overheated. There is no sweet smell of coolant from anywhere in the car.

seering

Had a very similar problem just recently.
I wound up being the neck of the surge tank.

I didnt think i was ever gonna find where my coolant was going.
Never saw puddles or any leakage .. but it kept coming up low.


I found it accidently by messing the the car hot and running, with pressure. I was gonna twist the cap just enough to let off some pressure and see if i was low and need to add. When i twisted the cap i hadnt pressed down hard enought and noticed coolant coming out where the neck goes into the surge tank. After toying around for 30 minutes i found my leak. Replaced that tank and havent had a bit of trouble since..


Now i wasnt getting the same amount of loss you were .. but it might be worth checking out.

rick lambert

I'd also get that puppy on some ramps,or up in the air and look very closely for any sign of coolant running down the block-then I'd start it up and do the same thing.Doesn't neccessarily have to leave a puddle,but could be a leak between the head gasket and block whereas
it only leaks while running (under pressure).I'm sure you've probably already inspected all hoses-same idea, some hoses only leak under pressure.

onevette01

I did the Dye test pretty cool glasses they give you, couldnt find any leaks anywhere. I pulled all the plugs out of it tonight I had changed them in November the plugs looked great not wet or any thing acually they looked almost new just a little black on the electrode. Im lost I need help. Some one said meybe a bubble internally But how would you releve that. Going Crazy. RJ

cv67

I'm thinking air pocket. Get the front end of your car elevated a bit--Pull your cap off, and let the car run. Be patient, the level can appear normal for awhile, then it'll belch some air, level drops, etc. Had this problem after replacing my intake: Had me stumped for a while..

Uh, let it run in park I meant. Or you could jack the front end up and toss it in drive just for effect

jamun

Let me recommend a cold system pressure test.

While on Jack Stands, top off the system and pressurize the system to about 16 lbs. when the entire system is cold. Coolant leaks are most likely to occur when the system is cold and pressure is present. This is going to require a cap like pump or some other device to do this. I have a homemade device that is a old cap with a brass fitting in the top. I hook this up to my compressor, and it works like a charm.

Hold this and begin to look at where it's going. It IS GOING SOMEWHERE!! I think you'll find it's a pressure leak, and probably somewhere not obvious. It's probably leaking out somewhere low and occurs while you're driving, not leaving a trace. If you cannot find the leak, then keep the pressure on until the system has de-pressurized; It will do this if you have a leak. If you still cannot find where it's going, drain the oil, as it’s likely leaking into the block and boiling away. Milky oil means you have water mixed in. If the engine gets hot enough, and the leak’s not very large, the water ends up boiling away and little trace of it can be found. The cold pressure test will keep this event from happening.

You’ve exhausted the easy finds…So you’re left with this process… Let us know what you find.

jamun

Oh, and I know this doesn't need saying....But if you use a compressor, make sure it's regulated at no more that 20 lbs. You don't want to pressure the system to 100 psi!!!

stevec4

Why not?

He'd sure as hell find his leak

onevette01

found the problem head gasket went on drivers side. Pulledoff the valve cover and inside the cover was covered in milky residue passenger side was ok clean well time to go to work wripping and tearing. thanks for all your ideas and help. rj save the wave