-
Coolant overflow leaking fluid out the cap
by
srgtlord
on 03 Jan, 2018 20:42
-
My 85 golf decided to start leaking fluid out coolant expansion tank cap today. Do these caps normally go bad after 34 years or do you think I have bigger problems? Any way to test the cap?
-
#1
by
Tmarkle
on 03 Jan, 2018 20:51
-
A cap is pretty cheap, might toss a new one on and see if it helps. If it’s not running hot I wouldn’t think there’s a bigger issue.
Sent from my iPhone using Tapatalk
-
#2
by
erichvw
on 03 Jan, 2018 20:53
-
My 85 golf decided to start leaking fluid out coolant expansion tank cap today. Do these caps normally go bad after 34 years or do you think I have bigger problems? Any way to test the cap?
Not sure but hopefully only a bad cap. Did the engine overheat? Worst case maybe a blown heat gasket.
Sent from my iPhone using Tapatalk
-
#3
by
srgtlord
on 03 Jan, 2018 21:02
-
No overheating. Car only went up to 1/2 temp on the gauge before I noticed the constant drip. Coolant lines felt pretty firm as well.
-
#4
by
erichvw
on 04 Jan, 2018 09:09
-
No overheating. Car only went up to 1/2 temp on the gauge before I noticed the constant drip. Coolant lines felt pretty firm as well.
I had a 2000 TDI with a blown head gasket. It would run fine in the city and not loose too much coolant for many days. Just some dripping. Coolant hoses would all become rock hard with pressure. If I took it on the highway for 10 minutes or so then the coolant cap would finally release a lot of pressure and burp out lots of coolant and it would immediately overheat. You could try running the engine at high rpm, maybe above 3000 rpm for 5 minutes or so and see if your coolant lines get hard.
Sent from my iPhone using Tapatalk
-
#5
by
srgtlord
on 04 Jan, 2018 12:15
-
Well I took the cap off and noticed the inside was covered in a black sludge. Actually there seems to be globs of black floating around the coolant system. I took a rubber glove and an elastic band and put it on the expansion tank. The glove did not inflate after a few minutes so Im going to say the coolant is not getting pressurized by combustion gasses. I cleaned out the inside of the cap with soap and water and the car went up to temperature with no leaks. So the next question is how the hell did black sludge get into the coolant system? Is it possible that an external oil leak could seep into a coolant hose?
-
#6
by
libbydiesel
on 04 Jan, 2018 16:21
-
It could be from the 'oil cooler', head gasket leak between the high pressure channel and a coolant passage near it, or a crack in the block or head. Oil cooler can be tested with compressed air and a bucket of water. Head and block can be pressure tested. Cracked block is least likely.
I would test the cooler first, then pull the head and inspect block/head. Have the head pressure tested if there is someone nearby who can do it. Measure for flatness. Measure piston protrusion. If those are within spec and there aren't cracks on the combustion face of the head, I'd replace the head gasket. Then clean the cooling system with dishwasher detergent and water.
-
#7
by
erichvw
on 05 Jan, 2018 12:42
-
Well I took the cap off and noticed the inside was covered in a black sludge. Actually there seems to be globs of black floating around the coolant system. I took a rubber glove and an elastic band and put it on the expansion tank. The glove did not inflate after a few minutes so Im going to say the coolant is not getting pressurized by combustion gasses. I cleaned out the inside of the cap with soap and water and the car went up to temperature with no leaks. So the next question is how the hell did black sludge get into the coolant system? Is it possible that an external oil leak could seep into a coolant hose?
Oil is leaking directly into the cooling system. Better that then coolant leaking into the oil. If you have milky white in your oil then that is probably coolant and the engine would not run for long. Probably head gasket or some other source. Perhaps you can just live with it if it's only a small oil leak into the coolant without it being pressurized. Depends how motivated you are to correct the problem.
Sent from my iPhone using Tapatalk
-
#8
by
fatmobile
on 08 Jan, 2018 13:12
-
There is a restrictor in that small line going to the reservoir.
Sometimes people remove them when they clog.
Then the coolant flows into the resevoir with more force slams up against the side and puts pressure on the cap,.. in addition to the normal pressure these pulses can be too much for the pressure relief valves in the cap.
Someone put a little deflector on the opening to direct this coolant downward.
-
#9
by
ORCoaster
on 08 Jan, 2018 18:56
-
I tried to run one of those clear filters prior to the reservoir in the hose as a way to catch gunk in the cooling system as well as see oil if it was there. I ended up pulling it off as it seemed to be too restrictive compared to the hose that just sprays it in. A deflector would help as it seems to hit the cap directly if you race the engine. Can only imagine what happens while driving.
-
#10
by
fatmobile
on 10 Jan, 2018 10:53
-
Riiiiight, you see what I mean.