Help with coolant leak

[fs34]

I recently addressed a leaking oil filter housing gasket. I replaced the coolant pipe O rings when I reinstalled the tstat housing. I can’t say that the housing felt snug when I installed it, but I went ahead and buttoned it back up.

For the ofhg job I had drained the radiator, so as part of refilling I applied vacuum via a Venturi kit(Schwaben from ECS). The system wouldn’t hold vacuum. I thought this might be due to low power/pressure from my little pancake compressor so I proceeded to fill the system and bled it normally. I started and ran the car for several minutes and coolant level seemed fine. Took it for a drive and when I parked it I could see coolant dripping from the opening in the reinforcement plate. Coolant level at the expansion tank went down.

I took the intake off and there was coolant down in the valley. I’m assuming this means a leak at the coolant pipes/tsat housing? I didn’t see any coolant dripping or running down anywhere on the front of the engine/belt area, if it is the tstat housing o rings, how did it get down to the bottom?

There are no other visible signs of leaked from the radiator, upper/lower hoses, expansion tank.

My question is, what other areas can I check for a leak? My fear is it’s something like the heater core or something I can’t see.

I’m open for any ideas, trying to gather info before I get back to it as I’m out of town for a few days.

Fingers crossed, I could use a simple fix(really hope it’s the tstat housing) after all of this.

Thanks!

[nrubenstein]

As a rule, focus on what you touched.

[fs34]

I plan to try the o rings first. Hope it’s that easy!

While I didn’t touch other areas, my concern is the vacuum I put on the system to remove the air, maybe stressed a hose somewhere I can’t see.

[SCREAM3R]

There’s a drain hole behind the flywheel that will drain liquid in valley. It will eventually just drip out from between the transmission and engine.

There’s 4 O-rings on that thermostat set up, two on each tube. Did you replace all of them? Mine were completely flat. It can be hard to tell that there’s 4 o-rings if the tubes are stuck in thermostat housing but they do come out.

[Helmsman]

Exactly the same thing happened when I replaced the thermostat a few weeks ago. Replaced all 4 orings, thought I was careful putting it back in place. Went for a drive only to have coolant pissing down the valley, doh!
Took it apart - this time with lubed hose connections on the plenum which made life much easier - only to find a cut oring. Replaced and lubed properly. Dry and nice since.
Oh, and the temp now goes straight up to 79C which wasn't the case earlier.

Good luck!

[fs34]

Originally Posted by SCREAM3R

There’s a drain hole behind the flywheel that will drain liquid in valley. It will eventually just drip out from between the transmission and engine.

There’s 4 O-rings on that thermostat set up, two on each tube. Did you replace all of them? Mine were completely flat. It can be hard to tell that there’s 4 o-rings if the tubes are stuck in thermostat housing but they do come out.

I only changed the 2 I could see on the pipes connected to the block, where are the other 2?

Oof, I need to get on realoem and look at the diagram. I feel pretty stupid now, really hope this is it!

Edit: I see where the other 2 go on the diagram. I’ll replace those and try again.

[Helmsman]

Originally Posted by fs34

I only changed the 2 I could see on the pipes connected to the block, where are the other 2?

Oof, I need to get on realoem and look at the diagram. I feel pretty stupid now, really hope this is it!

There are orings in both ends of the pipes. If you didnt pull them out of the house (or engine), its probably not leaking in that end. Might as well still replace them, a buck each. I thought even the new rings had a pretty loose fit and guess this is where the careful touch comes in, or they simply get cut on its way in.
Again, lube the pipes with grease and put straight in. You obviously also want to clean them and the engine side for the thermostat up.

The only other place it can leak around this area is the feedback hose from the thermo house to the coolant resorvar. If you didnt happen to break it already - easily done - put a tad grease here as well.

Cheers

[SCREAM3R]

Originally Posted by fs34

I only changed the 2 I could see on the pipes connected to the block, where are the other 2?

Oof, I need to get on realoem and look at the diagram. I feel pretty stupid now, really hope this is it!

Edit: I see where the other 2 go on the diagram. I’ll replace those and try again.

Yeah there’s 2 more but don’t feel bad about missing them. Like Helmsman said lube up those O rings when you put them in. If it wasn’t leaking before but now is it’s probably one of the newer ones not seating right.

[SAMM3Y]

Check the notorious small tank hose that runs across the top op the fan assembly into the thermostat house, when disturbed the end cracks off into the housing and causes a leak. You think it's fine because it's clipped in but if you can freely turn it, it's broken

[fs34]

Thanks all!

Now I’m itching to get to it, I’m 400 miles away from it. I’ll post here after I get back to it.

[fs34]

Originally Posted by SCREAM3R

Yeah there’s 2 more but don’t feel bad about missing them. Like Helmsman said lube up those O rings when you put them in. If it wasn’t leaking before but now is it’s probably one of the newer ones not seating right.

What lube do you recommend? Is dish soap ok? I’ve used a little dab of that before with some success.

[jellydoughnutt]

KY jelly is what I use. Any lube that is water soluble.

[acarr6]

This exact same scenario happened to me. Are you sure you didn't tear one of the O-rings? That's what happened to me. I took it apart and the new o ring I installed was torn. Make sure to lube it up a lot when reinstalling.

[SCREAM3R]

Originally Posted by fs34

What lube do you recommend? Is dish soap ok? I’ve used a little dab of that before with some success.

I used a little bit of oil which I’m sure isn’t the best because I have read it degrades the rubber but it was just a thin coat and I still believe it’s better than nothing. A small amount of liquid soap or some water soluble lubricant is preferred over oil I’m sure.

[Bubbles]

Check the connection pipes. Two rings per pipe.

[amrazM]

likely torn o-ring from installing the thermostat housing, the system not holding a vacuum is giveaway #1 there is a compromise somewhere within the system.

[M'EM]

Hey Guys,

I know this thread is old but I am in the same situation now. I changed the water pump and thermostat and replaced the two O-rings on the side of the tube that connects to the engine. The side that connects to the Tstat housing is tightly lodged so I dint mess with it. Put it all together and there was a leak when I started the car. So I took it out all apart and saw that one of the new Orings that I replaced was torn . I replaced it again and this time applied lube to both the Orings. I still dint replace the Orings on the Tstat side. I put it all together and the damn thing leaks again. I am at my wit’s end . I used a flash light under the plenum with the car running and can see that it is dripping from the Tstat/water pump area into the valley. I don’t see any coolant leak under the fan or hoses in the front. I ordered like 10 Orings and planning to replace all 4 this time. My question ( May be its a dumb question) is is there any way to know if the oring is broken or not seated properly before I put everything back on? Also are you guys lubing just the O-rings or on the metal tubes itself? Any tips/help will be appreciated..


The good part is I have become an expert in taking the Plenum off and putting it back together ..The second time I took it off and put it back together in 30 mins including changing the O-Ring..

[nick3753]

Originally Posted by M'EM

Hey Guys,

I know this thread is old but I am in the same situation now. I changed the water pump and thermostat and replaced the two O-rings on the side of the tube that connects to the engine. The side that connects to the Tstat housing is tightly lodged so I dint mess with it. Put it all together and there was a leak when I started the car. So I took it out all apart and saw that one of the new Orings that I replaced was torn . I replaced it again and this time applied lube to both the Orings. I still dint replace the Orings on the Tstat side. I put it all together and the damn thing leaks again. I am at my wit’s end . I used a flash light under the plenum with the car running and can see that it is dripping from the Tstat/water pump area into the valley. I don’t see any coolant leak under the fan or hoses in the front. I ordered like 10 Orings and planning to replace all 4 this time. My question ( May be its a dumb question) is is there any way to know if the oring is broken or not seated properly before I put everything back on? Also are you guys lubing just the O-rings or on the metal tubes itself? Any tips/help will be appreciated..


The good part is I have become an expert in taking the Plenum off and putting it back together ..The second time I took it off and put it back together in 30 mins including changing the O-Ring..

While I’ve not done it, I’m fairly certain you can start the car with the plenum off and run it briefly.

[M'EM]

Oh wow, dint know that. Can anyone who has done it confirm please? Anything specific to watch for if I were to run it for about 2-3 of mins to identify the source of the leak and then again when I fix it to confirm there is no leak?

[fs34]

The leak is from the o-rings. Replace all 4, then lube prior to reinstalling. Make sure the pressure is applied level when reinstalling and you can feel it going back into place. This solved my leak.

[fs34]

Originally Posted by Bubbles

Check the connection pipes. Two rings per pipe.

I removed these pipes to ensure I could see all 4. IIRC, the housing comes off easy and exposes the two that are on the side of the tstat, not the ones that we didn’t replace the first time. I actually found one ripped when I went back in to replace all 4.

[sergbaja5t]

FYI I've always used petroleum jelly to coat the o-rings in cooling system.