Last Lemming

I think I'm losing coolant but at such a slow rate I can't find the source. I can't tell if I'm losing coolant or not.

I put a mark on top of my coolant tank when it was completely cold where the coolant level was.

I drove about 15 to 20 minutes and parked the car. The next day I went and checked in relation to the mark and it looked like I was about 1/16 inch less coolant.

The only difference between the day when I put the mark and the day I checked it after driving it was about a 15 to 20° drop in the garage temperature.

So I went and got a pressure testing system and pressure tested the coolant system.

I pressure tested it to 11 psi and after about a minute or so it dropped to 10 psi and pretty much held there.

I tested for about 8 to 10 minutes.

While I was waiting for the pressure I checked under the car and there were no visible coolant leaks. There never have been.

The radiator is new, the radiator cap is a new, the water pump is new, and some of the hoses are new. I got under the car and looked at all the hoses from underneath and for that matter all the hoses above and I could not find any visible leaks before during or after the car was started and heated up.

The head gasket was replaced by the previous owner about 1500 miles ago. I suppose there could be a super small leak that is eating coolant however there is no water in the oil or oil in the water and when I left the pressure tester on while starting the car the needle stays steady but rises to about 13 PSI while the car began to heat up.

I also pulled all the spark plugs and everyone of them look exactly the same, they were perfectly colored with no wet spots or as if one was cleaned off.

I also went to the tailpipe and the normal condensation that comes out the tailpipe when a car warms up smelled normal. I even tasted it and nothing seems out of the ordinary. Tasted like water, but I suppose if I was leaking such a small amount I may not be able to tell.

Is there anything such as normal loss of coolant?

divil

Is that the only sign of coolant loss? 1/16th of an inch is nothing...you must have drawn a very fine line to even notice that lol! Honestly unless you're seeing a consistent drop I wouldn't read into it. You could check your reservoir cap and see if the seal is worn - that would allow some of the coolant to evaporate.

Last Lemming

Well the reason I marked a line in the first place was that I had filled the system to the max mark a few hundred miles ago when I replaced the water pump. Now it's about an inch or so from the minimum line. That's why I marked it and yes it was a fine line. Lol.

Oh I did bleed the system a few times too.

John_AZ

First, you have done most of the checks I would suggest.

I rented a coolant pressure tester and found a couple of tiny, pin hole leaks in the WP gasket on the '88. I changed the WP gasket last month and all is good.

There is no "normal" coolant loss but you may need to watch it for a few days until all the air pockets fill.

A more sensitive test than your nose or taste buds would be to use a leak down tester.
A check will show leaks into the coolant reservoir (or coolant into the block), exhaust and engine (hissing noise at the oil fill tube).
http://www.dietersmotorsports.com/Co...akdowntest.htm

Do you see a puff of white smoke out the exhaust about a minute after starting the car and about a block away from home?? Bad head gasket.

GL
J_AZ

Last Lemming

I had a leak down/compression test done about a month ago.

On 1,2,3,4 is came out 120,115, 115 and 110 on compression and 5,6,5,12% on leak down. Not great numbers to be sure, but she runs smooth and idles fine. The Porsche mechanic said the 12%. (#4 cylinder) was leaking a bit through the rings, but he detected no leak.

John_AZ

Good, then just watch your rear view mirror for the puff of smoke as you leave the driveway.

Your compression numbers are a little worse than "not great"

http://forums.pelicanparts.com/porsc...t-numbers.html

J_AZ

MAGK944

If it hasn't been bled completely and there is some air in the system you will sometimes get spurious levels at the tank. On a fully warmed up car try setting the heater on full hot and crank the bleed screw. I also find squeezing the top hose a few times while operating the throttle linkage helps dislodge the last air out of the system.

Last Lemming

Decided I would try to give the engine my own compression test. So I tested a cold engine and I came up with 140 basically across the board.

I'm not sure with the mechanic did you get such load numbers, maybe he did not open the throttle all the way. Idk.

John_AZ

A lot better!!

Maybe he forgot to remove the DME Fuel Pump relay when testing?

J_AZ

mytrplseven

+1

Last Lemming

I did all this when I was bleeding the system. But I can always try again I suppose.

odurandina

https://rennlist.com/forums/924-931-...-concerns.html

Last Lemming

Not sure why this link. I have read it before but that deals with water in the oil. I do not have water in my oil or vs versa.

william_b_noble

do not fill to "max", if it gets hot it will overflow some, or at least it can - just don't worry about it and watch it - keep it above MIN when cold.