Leaking Intake Gaskets

[wiberforce]

I just got my car back from being checked out for a CEL that i have had for so long and could not figure it out, the mechanic said that the car has leaking intake gaskets and is running lean and i know that its a big job so hes not going to fix it. The car runs good it just has a CEL and is running lean. Is this a hard thing to do myself? i have a lot of experience with working on engines.

[shogun]

it is not that complicated, it just takes time. Go to my website below, there is an excellent write up with plenty of pictures under
fixes>>>engine general>>>>Top end overhaul (M70 TOPEND RECONDITION) by George Fontes, 14 MB, 68 pages

DIY and you will be satisfied with the performance of your car.
Calculate with at least 1 day if you have never done it before, I now can do it in some hours. Prepare parts beforehand.

As George mentions: In my opinion, if one was just interested in replacing the valve cover gaskets & resealing the intake manifolds, the job could easily be done on a Saturday, but if more is planned such as drilling the oil-spray bar banjo bolts, safety wiring, repainting valve covers, replacing plugs, replacing hoses, rebuilding injectors, etc. one would be hard pressed to complete all these steps in a day.

[wiberforce]

ok doesnt seem too hard to do, should i replace the gaskets or reseal them? if replacing them where do you recommend i get the new ones from? i dont think the valve cover replacement is necessary they do not leak a lot unless you think i should do those as well while im at it

[shogun]

new gaskets cost you close to $500. I have never used new gaskets at the intakes, use liquid seal and you are fine with that.
As George mentions, when you have the intakes off, you can do many other things at the same time. Because to change the valve cover gaskets, you also have to take the intakes off again, otherwise. And that you do not want to do again. So make as much as possible when the intakes are off.
When intakes are off, you have the chance to do many things, you finally have SPACE there at the top end.
Even to change spark plugs is child's play then, replace the fuel lines in engine room, replace the vacuum lines in engine room, the return lines for fuel, and so on, just remember what you all wanted to do but could not, because there was no space and the intakes were in the way.

[wiberforce]

very true as always thanks for your input Shogun you are THE MAN, also one last question what do you recommend to use to seal it, brand and type a link would help, thanks

[shogun]

Read the instructions from George, he mentions:
Installing Manifold Gaskets
Apply the Hylomar sealant to the intake port gasket surface (do both banks). Apply a thin, even coat ensuring it covers the whole mating surface. (It might be easier to apply the Hylomar to the gaskets) Allow the sealant to flash off the solvent, then align the intake gaskets to their mounting studs and slide into place. Torque in a star pattern from the center out; snugging
them up in stages before applying final torque. (M8) 24 Nm ( ~18 ft-lb) These nuts use a 12mm socket.
Apply Hylomar to Intake Gaskets
This view shows a close up of the Hylomar applied to the gasket. You might consider applying it to the manifold flange instead, it’ll be easier and more accurate. I put too much on the gaskets below! Be sure to let the solvents flash off before installing the manifolds. Start with the right bank first - place the noise suppressor on the valve cover.
Mounting Intake Manifold, pre-steps
Before bolting down the manifold, you can position the noise suppressor by its bolts or just let it rest on the valve cover.
Next, align the studs on the plenum with their respective valve cover -mounted brackets. See below highlights. I also attached the ignition wire loom ........

[wiberforce]

okay thanks

[wiberforce]

a little bit of an update for you shogun today i disconnected my battery for about 2 hours or so and then i did the resync for the DK's and long and behold the surging has stopped im not sure if its because the car was hot but the car has not surged or ran crappy all day ill have to see tomorrow how it does on a cold start. It still has the CEL and thats from the leaking intakes which i will be resealing soon along with replacing the valve covers using the great guide on your site.

[SergeBMW]

Erich, or anyone who has done this before. Do you still recommend Hylomar as a sealant? I spoke to my Indy about this and he has done quite a few in the past, he recommended Toyota sealant used by the dealer. Is this really crucial or will most any sealant do?

Tackling this job today, I have the Toyota sealant that he gave me but it has an expiration date... Expires next month. Not sure if that is use by date or its effective date. If needed, I can buy Hylomar via Amazon prime 2 day shipping.

[shogun]

There is a long thread about sealant for the intakes in the E31 forum where they recommend Reinzosil https://www.bimmerforums.com/forum/s...ht=liquid+seal
In my opinion any sealant/liquid seal suitable for this application will do. We also have used in the recent years the Toyota sealant as this is easy to get here in Japan from the dealer. But also have used the last 3 times we did it last year with liquid seal we bought online.

[unity]

Compared to other goo I have used, Reinzol seems to bond very well to metal. Just make sure what you use is gas/fuel comparable. I used red RTV the first time - high temp, but NOT fuel friendly. When I re-did mine, the sealant came off way too easily.

[SergeBMW]

Hmm I will consider the Toyota one then since I have it, just worried about its expiration date. Im looking at reinzsoil, seems to be hard to find the specifics of each of their line up. They all simply say the basic use and that they are high temp. Will have to keep looking.

Unity, did you re-do yours due to it leaking again? I am hoping this repair will last a few years. I can deal with that.

[unity]

I re-did mine for two reasons. I rebuilt my top end. When I did, I used red RTV. But the ONE component group I did not replace, was my lifters. Bad idea, I should have. So I pulled the intakes to replace and noticed the poor holding of the red stuff. So I re-did the intakes with Renzoil. But my new Adjusa lifters were crap and noisy. So a couple months later, with them STILL making noise, I replaced them with good INA lifters. But it was REALLY hard to remove the Renzoil, even harder then the oil tolerant black RTV I use on the valve covers. Not impossible to clean off mind you, just a really nice sealed bond.

And yes, all that sealant cause I am pretty sure my gaskets leak. They are very cracked. However, I still have a bank throwing a code indicating an issue. I think my cracks are spread too far for the sealant to work well. I dont drive the 7 anymore and will have it sold without ever fixing the CE light. The fire plan was the thin die-cut silicone gaskets with Renzoil combination. Figured the two together might work well.

[SergeBMW]

My gaskets are not looking too great, there are cracks on the inner portion of the gasket. Seems it should not affect the actual sealing though, as that portion seems intact. Sadly I failed to purchase the Renzosil online due to needing to get the car back together quickly. I got delayed with the valve cover sand blasting and painting, by now the Renzosil would have arrived.... Now I have to put it back together by tomorrow and still dont have a sealant. I may head over to a Toyota dealer and see if they have that sealant that Erich has used over in Japan. Not sure if they sell that at the parts department of the dealer. Crossing my fingers.
The sealant I have does not seem to be working properly, maybe due to its expiration date. I tried gluing 2 things together and adding some pressure over a long period of time. They came apart fairly easily, not too convincing. I'd hate to go back and remove the intakes again due to a bad job.

[unity]

If the cracks go past the intake casting, then they may still leak. I think that is my issues, cracks too deep. Its amazing what a small hole can do. Think of a drinking straw with a tiny hole.

[shogun]

how about the intake silicone gaskets from Max Lumens? https://www.bimmerforums.com/forum/s...70+intake+seal