Kind of "Mystery" Coolant leak back of engine (heat exchanger valley leak)

[sdnative]

You can also soak the o-ring in coolant to lubricate. Not sure if the grease will contaminate the coolant.

This is what can happen if you install the union pipe with a dry o-ring. Make sure you check it before re-installing the cover so you don't have to take it apart again.

 

[todiy]

I saw your post and that's why I decided to lubricate with extremely small amount of grease (~1/10th gram) which really helped and made it easier. As for contamination, I have taken this risk and we'll find out in time if it has any drastic consequences.

 

[dubaicruiser]

Since I realized I had this same leak after posting, just wanted to leave my thread with pictures here also.
Mine is a 2014 LC200 4.6L V8. Caught the leak at 140k km service.

Coolant leak, probably at heat exchanger

Hi guys, while doing my 140k kms service,they caught a coolant leak. Coolant was low so did a pressure test as it was not dropping externally. Attaching the pictures. what do you guys think? Its a 2014 vxr V8 4.6L,GCC specs. URJ202L

forum.ih8mud.com

 

[Supra88]

I'm losing coolant, but can't find the location. I put my scope camera under the manifold but couldn't find anything. Have all of you been able to see the leak without taking off the intake manifold? Any other tip to seeing under there?

I pressurized the the system and found I had a very very slight degradation in pressure after 15 minutes, but still couldn't find the leak. It has a new radiator, pump, tees, etc already.

 

[bloc]

I'm losing coolant, but can't find the location. I put my scope camera under the manifold but couldn't find anything. Have all of you been able to see the leak without taking off the intake manifold? Any other tip to seeing under there?

I pressurized the the system and found I had a very very slight degradation in pressure after 15 minutes, but still couldn't find the leak. It has a new radiator, pump, tees, etc already.

Were you able to get to the back of the coolant valley plate? Some of the pictures I’ve seen have the leak mostly in the back.
If not there other possible mystery leak locations are the transmission fluid heat exchanger in the radiator, oil cooler letting coolant into the oil pan, heater core either in front or back, or the lines going to the back. Though I can’t recall seeing anyone have issues with these places.. it’s just possible for coolant to disappear with leaks there.

 

[Supra88]

Were you able to get to the back of the coolant valley plate? Some of the pictures I’ve seen have the leak mostly in the back.
If not there other possible mystery leak locations are the transmission fluid heat exchanger in the radiator, oil cooler letting coolant into the oil pan, heater core either in front or back, or the lines going to the back. Though I can’t recall seeing anyone have issues with these places.. it’s just possible for coolant to disappear with leaks there.

I was not able to get to the back. Is there access from the back of the manifold where I could get my scope in?

 

[bloc]

I was not able to get to the back. Is there access from the back of the manifold where I could get my scope in?

I don’t think so. There should be a foam block similar to the front and the air injection valves are back there too, though I’m not sure the extent to which they block things. I just think successfully getting a camera in around the foam could be a challenge.
Removing the manifold actually isn’t all that difficult... it is o-ringed so there isn’t a gasket to deal with, no cooling lines, just some harnesses and valves bolted on top. but I do understand not wanting to go that far unless needed.

 

[Supra88]

I don’t think so. There should be a foam block similar to the front and the air injection valves are back there too, though I’m not sure the extent to which they block things. I just think successfully getting a camera in around the foam could be a challenge.
Removing the manifold actually isn’t all that difficult... it is o-ringed so there isn’t a gasket to deal with, no cooling lines, just some harnesses and valves bolted on top. but I do understand not wanting to go that far unless needed.

That's a walk in the park compared to the work I just finished on the 200 - lol. I'll pull the manifold off since this is likely the culprit.

 

[Supra88]

Well I got my scope in behind the manifold. I'm at 230k mikes, does it make sense to replace any of the air injection stuff or anything else while I'm in there?

 

[bloc]

Well I got my scope in behind the manifold. I'm at 230k mikes, does it make sense to replace any of the air injection stuff or anything else while I'm in there?

View attachment 2481494

View attachment 2481495

No, I wouldn’t replace anything else that isn’t bad. And make sure you get the updated sealant.

Be careful with the stainless pipes from the exhaust manifolds to the AIC valves.. getting everything loose sounds like a challenge and a couple people have cracked those pipes at the weld/flange from being too aggressive with them.

 

[Supra88]

Any tips to disconnect the harness attached to the back of the intake manifold? Edit: I ended up unbolting both harness clips from the manifold.

definitely had a leak for a long time.

 

[Supra88]

What a hot mess. Did you take out what appears to be the knock sensors?

 

[sdnative]

What a hot mess. Did you take out what appears to be the knock sensors

I did. Wasn't sure what they were but that makes sense. Much easier to set the HX lid back in there and not bugger up the sealant bead without the sensors in the way.

 

[PDoyle]

Good times!

 

[Supra88]

Couple more questions. When putting the orings on are you guys connecting one of the sides before final install? Which side?

I removed the cover with the studs in place. Did anyone remove the stud(s) before installing or were you able to get it in place leaving them?

 

[sdnative]

Which orings? On the union pipe?

I removed the studs (should be two of them I think?), but I don't think you have to if you have enough clearance. I had to buy a special female torx socket, forget the size.

Edit: the female torx socket I used was 1/4", found at my local lowes / home depot.
Edit 2: not a torx just an 8-point socket see below

 

[Supra88]

Which orings? On the union pipe?

I removed the studs (should be two of them I think?), but I don't think you have to if you have enough clearance. I had to buy a special female torx socket, forget the size.

Edit: the female torx socket I used was 1/4", found at my local lowes / home depot.

Excellent thank you. I'm going to pull them to make the reinstall as easy as possible.

 

[sdnative]

This is what I used. Yes Lowes sells craftsman now. I don't think it actually a "Torx" but rather just an 8-point socket.

 

[bloc]

Technically an “e-torx” bit will work best on that. Im not sure of the size, but I have a set at home and you’d be surprised where those studs rear their head. (Get it?) Exhaust manifold, down pipe, few other places.

 

[Supra88]

Technically an “e-torx” bit will work best on that. Im not sure of the size, but I have a set at home and you’d be surprised where those studs rear their head. (Get it?) Exhaust manifold, down pipe, few other places.

I was able to use a 6mm 12 point to get one off, but will grab the e-torx to take the other one off and reinstall them.

I was surprised how much coolant was in there. That's a small swimming pool. Hoping to to do the install tomorrow.

word of advice: i unbolted the passenger side valves from the manifold and it was super simple. Highly recommend taking that route.