Help - coolant in the valley - why?

[BostonJon]

A little update....

Last night I finally tore into the project and got the intake manifold off. I found quite a bit of coolant in the area under the intake manifold. Interestingly, there was green coolant (previous owner) and red coolant (I flushed with distilled water and switched to Toyota red when I bought it) under there. I noticed that the intake manifold gasket - particularly the front and rear channels where coolant flows - were pretty badly corroded and no longer had any of the rubber around the mating surface. My theory is that this allowed coolant to seep out through the mating surface between the intake manifold and the head. Most of it likely burnt off when the car was hot but when the car was cool, it seeped into the valley and down the back of the head and onto the ground. I think this is why I was seeing more coolant on the ground after the car had been sitting for a while.

I don’t think the water bypass pipe was leaking but I replaced it while I was in there. Also swapped out the knock sensor harness. I did not have time to get everything back together so I don’t yet know if this will solve the problem, but from what I’ve seen in there I’m optimistic that I found the issue.

I’m going to clean my injectors and put on new o-rings later this week and get it all buttoned up and test it.

Stay tuned....

 

[Mantilgh]

Edit: Just saw your last post.

I’d imagine that those gaskets were the problem then.

Good luck with it!

 

[BostonJon]

Edit: Just saw your last post.

I’d imagine that those gaskets were the problem then.

Good luck with it!

I checked out all the heater hoses because that would have been the easiest fix. They were all dry and there was no explanation for coolant in the driver side valley.

 

[19963.4lsr5]

That happened to the 97 Limited Puppy hauler. Since I had the intake off I had the heads gone over. Valley full of coolant.

Getting a good bead of sealant on the bypass tube was a challenge. I don’t know why an o-ring wouldn’t have worked.


Sent from my iPhone using Tapatalk

 

[jkoni426]

A little update....

Last night I finally tore into the project and got the intake manifold off. I found quite a bit of coolant in the area under the intake manifold. Interestingly, there was green coolant (previous owner) and red coolant (I flushed with distilled water and switched to Toyota red when I bought it) under there. I noticed that the intake manifold gasket - particularly the front and rear channels where coolant flows - were pretty badly corroded and no longer had any of the rubber around the mating surface. My theory is that this allowed coolant to seep out through the mating surface between the intake manifold and the head. Most of it likely burnt off when the car was hot but when the car was cool, it seeped into the valley and down the back of the head and onto the ground. I think this is why I was seeing more coolant on the ground after the car had been sitting for a while.

I don’t think the water bypass pipe was leaking but I replaced it while I was in there. Also swapped out the knock sensor harness. I did not have time to get everything back together so I don’t yet know if this will solve the problem, but from what I’ve seen in there I’m optimistic that I found the issue.

I’m going to clean my injectors and put on new o-rings later this week and get it all buttoned up and test it.

Stay tuned....

I have the same thing happening, thought it was the bypass pipe but haven't dug into yet. Definitely interested in what you find, I've just been topping off the coolant reservoir every couple weeks for about the last 5.5 years now ha.

 

[BostonJon]

attached is a picture i took the other night, which i think makes it pretty obvious what was happening. at the bottom of the picture (front of the truck) - especially on the right (driver) side - you can see the pink coolant that was in the valley. you can also see that the rubber gasket material around the dual coolant passage ways was in pretty bad shape. most of it was still stuck to the head when i took the old metal gasket off. there was also some more minor leakage (seepage?) on the passenger side (left side of the picture) at the single coolant passageway. I think the rearmost passageway gasket was bad too and this is the leakage that I was seeing down the back of the motor and onto the bell housing. the coolant leak in the front was making its way down behind the timing belt and onto the water pump housing. i thought i also had a water pump leak but I'm hoping it was just coolant dripping down.

I never had the telltale white smoke of a head gasket failure so I think my leak was luckily limited to the valve cover gaskets.

i should note that this was a tedious and time consuming job, but not a particularly difficult one.

i may put some threadlocker on my valve cover bolts because I realized that they were extremely loose already after re-doing my valve covers less than a month ago. no wonder so many of us have VC leaks.

 

[BostonJon]

I have the same thing happening, thought it was the bypass pipe but haven't dug into yet. Definitely interested in what you find, I've just been topping off the coolant reservoir every couple weeks for about the last 5.5 years now ha.

i noted this above, but i'm fairly confident that my bypass pipe was fine. the FIPG material on the mating surface of the pipe and head was still pliable and I did not see any corrosion around the mating surface. how that I see how/where it is mounted, I don't think a bypass pipe leak would show up as coolant in the valley because the valley is situated higher than the bypass pipe. rather, a bypass pipe leak would fill the cavity under the intake manifold and drip down the back of the engine (the only way out).

in hindsight, it seems logical that the mating surface of the intake manifold gasket would be suspect - especially if it's never been replaced. in my naivety, i didnt know that coolant circulated through the intake manifold. had I known that, I might have suspected this gasket in the beginning.

 

[RS Dude]

I would buy some new Densos off ebay for about $25 a pair. Also, with a soft metal brush, clean off the mating surfaces of the intake manifold and cyl heads before you put on gaskets.

 

[BostonJon]

I would buy some new Densos off ebay for about $25 a pair. Also, with a soft metal brush, clean off the mating surfaces of the intake manifold and cyl heads before you put on gaskets.

that's what i bought. i plugged the valve holes with some painters tape and used a soft wire brush on a the end of a drill to carefully clean the mating surfaces. it cleaned up nicely and everything is back together. I just havent had time to get the plenums back on, refill with coolant, and test it. maybe this weekend i'll get to it.

i should also note that the recommendation in post #16 from gamefreakgc was spot on.

 

[SilverRidgeRunner1]

Well was this a successful resolution to your problem

 

[BostonJon]

Well was this a successful resolution to your problem

Not sure yet. Haven’t gotten it all back together and filled with coolant. It’s not my daily driver so sometimes it’s sits a while until I can find the time to spend in the garage. I won’t forget to update the thread when i have an answer. However, given the shape the old gaskets were in and the pic I posted above, I’m pretty confident I solved the problem.

 

[BostonJon]

Success! All buttoned up and no more leaks!

I changed out a few vacuum and heater hoses while I was in there. Also put some threadlocker on my VC bolts because they kept coming loose.

One other unexpected benefit - when putting everything back together, I took some of the slack out of the throttle cable and trans kick down cable. Much much more responsive throttle now.

 

[jkoni426]

Nice, congrats! This is most likely the same issue I've been dealing with. Now I just need to find the motivation to tackle this...

 

[BostonJon]

Nice, congrats! This is most likely the same issue I've been dealing with. Now I just need to find the motivation to tackle this...

it really wasn't all that difficult, just very time consuming. it could probably be knocked out in a day if you had all the parts ready and had some extra heater and vacuum hose ready just in case. it was a rewarding job to have completed though. leaks drive me crazy and I'm working my way from top to bottom taking care of them one at a time. most of the upper stuff is done now (valve covers, half moons, cam plugs, plenum gaskets, intake manifold gaskets) - now moving down to oil pan and trans pan.

 

[jkoni426]

Finally got this knocked out this past weekend... replaced injectors with GB remanned oem, oem intake manifold gaskets, oem plenum gaskets, and oem knock sensor harness while in there. Good call on the knock sensor harness because it crumbled in my hand as I was removing it. So far so good, guess time will tell.

Thanks for the motivation!

 

[2owner4runner]

lots of good info

I learned a lot from this post

 

[EvergreenPearl]

Thanks for this thread. Dug into VCG job tonight and noticed lots of crystalized coolant in that valley, drivers side, mostly towards the front, just like yours. I was thinking head gasket until I saw this thread.

Hopefully my issue is the same as yours and not worse. Will take another look tomorrow and pull the intake manifold and expect to see leaky intake manifold gaskets.

Thanks again for this info.

 

[SilverRidgeRunner1]

Thanks for this thread. Dug into VCG job tonight and noticed lots of crystalized coolant in that valley, drivers side, mostly towards the front, just like yours. I was thinking head gasket until I saw this thread.

Hopefully my issue is the same as yours and not worse. Will take another look tomorrow and pull the intake manifold and expect to see leaky intake manifold gaskets.

Thanks again for this info.

Yep sounds about right did this same repair at the same time he did, and wa la also not sure if he completed the same steps but I ended up having to replace the freeze plugs under there while I was at it they seemed corroded and didn't want to deal with this twice.

 

[BostonJon]

Thanks for this thread. Dug into VCG job tonight and noticed lots of crystalized coolant in that valley, drivers side, mostly towards the front, just like yours. I was thinking head gasket until I saw this thread.

Hopefully my issue is the same as yours and not worse. Will take another look tomorrow and pull the intake manifold and expect to see leaky intake manifold gaskets.

Thanks again for this info.

good luck! let us know what you find

 

[senordan]

I recently changed my lower intake manifold gasket due to the rough idle and pooling coolant. Several lessons I've learned, make sure you offset the knock sensor wire on the left (passenger side) so you don't get a P0330 code.
If the plastic cover for the wires becomes brittle and breaks off, make sure you protect it with something. I found Rustoleum's Leakseal is a cheap alternative to rescue tape and is rated to 500 deg F.