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Geinko

96 Eldorado Coolant leak(under intake manifold)

13 posts in this topic

Hello everyone, 96 Cadillac Northstar 4.6L
Symptoms high idle and constant revv 
So I pulled the Intake manifold and coolant started to leak out of the bolt hole(Closest to plug 8) under the intake. Picture included, the leak will stop with the bolt hand tight with the intake off. No Codes.
I am wondering is this a head gasket or something else? Would sealant be a bad idea?

PS Picture I grabbed from the internet. My car is not this dirty ;)

post-418-1180406322.jpg

Edited by Geinko

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There should not be coolant at that bolt hole. Could be a crack in the coolant passage from the crossover. Pull the crossover manifold and check the passage. Check the throttle body gasket at the intake plenum for a leak especially at the bottom, that could have been the cause of the high idle.


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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15 hours ago, OldCadTech said:

There should not be coolant at that bolt hole. Could be a crack in the coolant passage from the crossover. Pull the crossover manifold and check the passage. Check the throttle body gasket at the intake plenum for a leak especially at the bottom, that could have been the cause of the high idle.

Thank you for your comment. I agree. I will post a picture of my car. Let me know if could still be the crossover. 
I am renewing the gaskets before i put it all back(my intake plenum is o-ring style). 
I am thinking of draining the coolant so everything will go on dry, then use a little gasket maker at the top of the hole, 

018dab232626f235a05673cb0309c6601c82ee463a.jpg

Edited by Geinko

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Welcome to caddyInfo.

I can honestly say I have not seen one do that before.

Is that a open bolt hole (deep into the head)

or is it shallow (bottoms out a little ways down)

I am thinking there may be a hairline crack somewhere  and the coolant is seeping out of there. Need to think on this one

I might add excellent post and pictures


GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Very strange.  That is the intake bolt, correct?  Those holes are not into the water passage of the head from what I recall.  I wouldn't suspect the leak source to be in the water crossover.  Besides, that thing is a royal SOB to R&R with the engine in the car.  I would drain the coolant, then clean the threads in the head, and use some GM Engine sealant on the threads of that particular bolt when you install the intake.  Let the sealant cure before refilling the coolant.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The hole is in the head, and it should be a dead end hole. BUT if someone installed the bolt with liquid in the hole it is easy to "crack" open the bottom of the hole by hydraulics The bottom side of that hole is in the coolant passage that the crossover connects to. if you fill the hole with sealer you will create another hydraulic condition that can make it worse.

You might be able to do as KHE suggested and lower the coolant level enough to inspect the bottom of the hole with a bore scope or maybe a good magnifying glass.

The crossover pipes are a "&!%@%" to do but you will be able to see more of the passage/cavity with it off. The head at the front of the vehicle can be changed with the engine still n the vehicle which is an even bigger "&!%@%".

If the bolt hole goes into a big enough cavity, you would be better off to drill and re-tap the hole completely through, then use sealer on the threads of the bolt.

If someone has a head laying around they could take a look at the passage and let us know if there is enough room in the passage.

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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I was suggesting coating the threads of the subject intake bolt, not filling the hole with sealer.  That would not create a hydro lock condition.  My thought is that with the threads sealed, the coolant could not leak into the valley under the intake.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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@KHE I wasn't referring to your post, I was referring to the OP statement about making a gasket. Only reference I was making to your post was the crossover being a PITA but breaking the head is a much bigger PITA. 

The head is obviously cracked already at the bolt hole. If it is just cracked at the bottom of the bolt hole and there is room in the coolant passage to drill the crack out then seal the bolt, it should work fine. If the crack is through the threads the only hope is an insert or head replacement. Without seeing into the passageway it is going to be hard to determine if it is fixable or if it will require a head replacement. That is why I recommended the removal of the crossover, to see the extent of the crack.

If it does need a head replacement the crossover would have to come off anyway.

There is another alternative, put it back together and pretend nothing is wrong. 

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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I agree on the fluid being in the hole. 

It must be a stress crack. I wonder if putting some sealant in the threads of the bolt only could resolve the issue.

The bolt would have to be tightened and not budged after it cured.

Also would not want to get sealant under the bolt in the hole for the same reason of compression.

It all varies on how much pressure is pushing from the hole and where the crack is as to whether it will get larger and continue to leak


GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Can you use a mirror to see if the coolant is leaking externally (under the area where the bolt hole is)?  If it is not, the fix may be as I described in my earlier post.  Add a tube of Bars Leaks to the upper radiator hose and refill the coolant.  That might be enough to stop the leak.

I'd be tempted to try that vs. pulling the water crossover and replacing the head.  The front head would be easier to R&R than the rear head with the engine in the car but it is still going to be a huge job.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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On 2/14/2017 at 7:23 AM, KHE said:

I was suggesting coating the threads of the subject intake bolt, not filling the hole with sealer.  That would not create a hydro lock condition.  My thought is that with the threads sealed, the coolant could not leak into the valley under the intake.

I drained the coolant and everything was dry when I pulled the bolt. I am doing as you said. I now have to intake manifold back on made sure everything was clean and dry now waiting until tomorrow to fill up the coolant.

22 hours ago, rockfangd said:

I agree on the fluid being in the hole. 

It must be a stress crack. I wonder if putting some sealant in the threads of the bolt only could resolve the issue.

The bolt would have to be tightened and not budged after it cured.

Also would not want to get sealant under the bolt in the hole for the same reason of compression.

It all varies on how much pressure is pushing from the hole and where the crack is as to whether it will get larger and continue to leak

I believe in your comments and would like to stay optimistic.

On 2/14/2017 at 2:40 PM, OldCadTech said:

The head is obviously cracked already at the bolt hole. If it is just cracked at the bottom of the bolt hole and there is room in the coolant passage to drill the crack out then seal the bolt, it should work fine. If the crack is through the threads the only hope is an insert or head replacement. Without seeing into the passageway it is going to be hard to determine if it is fixable or if it will require a head replacement. That is why I recommended the removal of the crossover, to see the extent of the crack.

If it does need a head replacement the crossover would have to come off anyway.

There is another alternative, put it back together and pretend nothing is wrong. 

I believe the threads are fine because I was able to plug the hole and stop the leak with the bolt. Yes I agree now that the head is cracked, and replacing it would be the best option. But I am trying out a temporary fix because I lack experience, time, and resources. It would be cheaper for me to buy a parts car rather then finding a head(This is the price of living in hawaii). I really do like your suggestion of removing the coolant crossover to examine the damage. I think that is spot on in my situation. 

Thank you everyone for your time and knowledge. I am surprised on how quick you guys are at caddyinfo! I am on Hawaii time so sorry for the delay. 
I think I have found the air leak causing the high idle which was the reason for taking things apart, see picture of intake manifold gasket. 
Hopefully everything works out and I will be back with good news.

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Edited by Geinko
rockfangd likes this

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Yes, it looks like you found the vacuum leak, that's good news. :shaka:

I'm curious, was the damaged gasket you have pictured at the intake runner where the bolt hole crack is?

 

 

 

Edited by OldCadTech
Deleted content

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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6 hours ago, Geinko said:

drained the coolant and everything was dry when I pulled the bolt. I am doing as you said. I now have to intake manifold back on made sure everything was clean and dry now waiting until tomorrow to fill up the coolant.

OoOps - never mind..... skipped right over that statement, LOL >>>> Good luck in the morning...


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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