Intake manifold leak

[RODRIG3911]

Hello fellas!!! So I replaced my intake manifold a few months ago and my Broncos been running fantastic (Especially with the Holley Sniper system). I went on about a 5 hour long journey up and over a 9000ft mountain with a rough off road trail for half of it and developed a leak on the front of my intake manifold (I used no gaskets on the front, just permetex black).... Now this leak doesn't start until I drive my Bronco for about 30 minutes, and then you can see a very small leak that pools up on my timing chain cover.

Question is, should I take it off and give it another shot, or has anyone had any luck with a special chemical sealer that I can pour in with the oil that could bond and stop it... Everything else sealed up perfect expect that one spot

 

[SteveL]

Probably a redo. I've never had much luck getting things to seal once they're leaking. You can try torqing it down more to slow the leak but it's still gonna seep.

 

[RODRIG3911]

Steve, I'm sure you're right man. I just don't know that I am good to do it again from scratch without any issues lol.. Got any good tips for sealing the front and back? I used permetex Black with no gasket and let it set for a few minutes before installing the intake. I used studs for a guide to not move it while seating.... Maybe permetex black isn't the right sealer?

 

[SteveL]

That's how I do it. I use the blue felt pro gaskets but not the cork or rubber ends. I usually use the blue rtv. I've also used edelbrock gaskacinch but not always. Its sticky like glue to stick the gasket down.

 

[RODRIG3911]

Cool. Thanks man. Guess I'll try it again when I get a spare few hours. I know you're right about doing it over is best

 

[jckkys]

I'm assuming you took the back road up Mt. Lemon. Fun drive, that's no challenge for an EB. I would make sure the coolant isn't coming from the thermostat housing. The puddles end up in the same place. It's an easier fix. I have yet to get the intake installed without small leaks at the corners. So I too want to hear better techniques.

 

[SteveL]

X2 on the stat housing. Especially if it's one of those purdy aftermarket ones. The aftermarket ones are rarely flat and always leak. Get the cheap cast metal one from the local ap store. They seal up nice

 

[RODRIG3911]

jckkys Yes sir, it was Mt Lemon. Easy run, but still pretty far drive for the Bronco having to go all the way around Oracle. It was beautiful!!! I saw 2 turkeys and a big deer.

Unfortunately It was oil and not coolant. I can see exactly where it's seeping out. I will try to work on it a little here and a little there to hopefully get it done by the end of next week. The weather is too nice right now to have Bronco problems

Here's a couple pictures of the Mt Lemon adventure

 

[blubuckaroo]

Anytime you use RTV, it's really important to clean the surfaces really oil-free.
I like to use Berrymans Chemtool, but lacquer thinner works well too.
Bottom line is it's got to be dry.

 

[RODRIG3911]

Thanks man! I did clean it well, but it may have been a little oily. This next time it'll be super dry

 

[73azbronco]

oil leaking out at that place would be odd I think, most anything gets sucked in, except coolant. If its oil, are you sure you don't have a valve cover leak, timing cover leak? I don't think there is any pressurized oil under or through the intake manifold, so any leaking out is unpressurized.

Does it run well, still have same vacuum? If so, I would think intake is good, its from somewhere else.

PVC leak?

 

[RODRIG3911]

Hmmm, you've got me thinking now!.. It sure looks like it's coming out of the front of the intake manifold, but you're right that it would mean I have a lot of high pressure oil high up in the engine.. I'll have to clean the area really well and start investigating again. It runs fantastic!! My Sniper efi's afr's do fluctuate a bit more then I'd like, but that could also be my tune still learning.

 

[jckkys]

Oil doesn't have to be under pump pressure to leak. Valve covers, oil filler caps, breathers and PCV valves/hoses all leak with no pump pressure. The oil mist in the crank case. lifter valley, and under the valve covers seeps out. I think it's partly wicking action and partly the pressure of blow by when the engine is under load. The silicone rubber front and rear intake to block seal always leaks a little.

 

[valveamp]

My original timing cover was corroded at the top. There was always oil in those little valleys above the timing cover and below the intake manifold. I never could figure out what what going on. I thought it was the manifold also. One day, I rev'ed the engine up by hand (above idle) and took a close look at the leak area. Sure enough, when the RPM was high, I could see oil being forced out of the top of the timing cover. Didn't see that when it was just idling. A new cover took care of the problem. My memory is that the cover was aluminum, but now I'm not sure. It was several years ago.

 

[RODRIG3911]

That’s a good point how low pressure areas like valve covers leak. It sure looks like its the intake.. I’ll have to look closer

 

[blubuckaroo]

Oil puddling up in the pockets on top of the timing cover is pretty common. It usually comes from a leaky valve cover or the corner of the intake manifold seal. Both of these are a pretty easy fix.
Even though both these areas are low pressure, a bit of pressure can develop in an crankcase, especially if the PCV system isn't clear.

 

[Rustytruck]

When i seal the ends of the intake i clean the old silicone to bare metal and use an acetone wipe of the surfaces. Then i thinly seal the surfaces with silicone and let the silicone fully set up. After set up a then put the heavy bead of silicone on the block ends and drop down the intake and start the bolts and run the bolts down but dont torque them yet. Let the silicone set about an hour so it skins over. Then torque the intake. This method works best for me.

 

[blubuckaroo]

When i seal the ends of the intake i clean the old silicone to bare metal and use an acetone wipe of the surfaces. Then i thinly seal the surfaces with silicone and let the silicone fully set up. After set up a then put the heavy bead of silicone on the block ends and drop down the intake and start the bolts and run the bolts down but dont torque them yet. Let the silicone set about an hour so it skins over. Then torque the intake. This method works best for me.

Good advice.
This is exactly why so many rear main seal replacements fail. Clean dry surfaces are the key to using sealants.

 

[RODRIG3911]

Great tips guys! It definitely was coming from my intake manifold... Yesterday I dug into it after a 12 hour night shift lol... All I have left to do is stab the dizzy and wait the 24hrs for the RTV to dry. Thanks again for the help ;D

 

[nvrstuk]

Double check the timing covers too.

I totally disagree about oil leaks in the frt and/or rear intake valley areas. Sorry, but done right, they won't leak even after 100K miles.

When you think you've cleaned the surfaces enough, get a white paper towel, put some rubbing alcohol on it and wipe the mating parts... if it stays white...you won't have a leak. If you stop wiping it down before the paper towel stays white after wiping it down... you AIN'T DONE YET.

Having the silicone seal is dependent on the mating surfaces being spotlessly clean. Think of it as paint prep..it's gotta be almost that clean.

Good luck

I called Permatex last year when I was looking for a sealant...ask the tech I was talking to about using an RTV type sealant. he said to never let it "set-up" or skin over. To seal it needs to actually bond to both surfaces and if it skins over it won't. Call them up- see what they say.