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  #1  
Old 12-23-2005, 02:41 PM
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Join Date: Nov 2005
Location: Illinois
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Intake Manifold Gasket Air Leak - Help

I just replaced all of my glow plugs in my 87 300D w/277k miles. I took off the intake manifold in doing this job and installed a new gasket. I noticed that the gasket slide easily around as I was reinstalling and I was not sure that it was dead center where it needed to be. Well...when I got everything back together...I noticed that I now had a whistling noise coming from under the hood when the turbo kicked in. I then diagnosed and it seems to come from 1 or 2 intake manifold ports where the gasket is (intake to engine block). There even seems to be a little oil lightly spraying in the general area which also confirms that there may be a slight air leak. I am planning to loosen the intake manifold....try to reposition the gasket and then retighten.

1) Are there are any techniques that would assist me in getting the gasket exactly where I want it when putting it back together? (put a little oil on it to get it to stick better rather than slide?)
2) Should put on a new gasket rather than reuse the one that I just put in? (I have a new one coming)
3) Are there any things that I should be considering in trying to do the job without air leaks this time(assuming that that is the source of the whistling noise).
4) Do people sometimes take off the intake manifold w/o taking off the fuel lines? (I don't want to break anything).

As people may be able to tell....I am no mechanic....just a enthusiast who has recently trying to resolve some issues myself without taking it to a garage....and I take my time and go slow when working on the car!

Thanks.

-------------------
1987 300D 277,000
1995 E300 128,000

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1987 300D (277,000)
1995 E300 Diesel (122,000)
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  #2  
Old 12-23-2005, 03:04 PM
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Join Date: Feb 2004
Location: Ontario, Canada
Posts: 491
On a 603 engine there shouldn't be any 'slip' of the Intake gasket with all the bolts that locate the manifold. I would strongly recommend using a new gasket as the old ones harden and leak quite easily. Mine was leaking slightly around the #2 intake runner. Make sure the face of the manifold is straight and even and that there is no crud or gasket material on the seating surface. Be sure to use the correct tightening torque when installing, it is easy to strip the aluminum threads in the head

Use one bolt at each end to locate the gasket onto the manifold as you position it on the head. Use cotton thread or fishing line to keep in place if neccessary while you start the bolt threads. Remove the thread/line before you tighten down the manifold. Run all the bolts into place before finally torquing them down.
If there is whistling around the intake then it is probably your old gasket.
You might want to use a new gasket on the cross-over pipe as well.
I don't think you can remove the manifold without un-clipping all the fuel lines - at least not without a lot of extra work. Buy some new plastic clips from the dealer in case you break any during disassembly.

Good Luck
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  #3  
Old 12-23-2005, 03:38 PM
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Thankyou. Your instructions will be very helpful....especially to be careful not to over-torque. I have replaced all new clips already for fuel lines as the old ones were brittle and breaking. I did install brand new gasket so I must have it misaligned on one of the intakes...or...

I am now starting to wonder if maybe I put the glow plug harness attachment on 2 of the intakes in the wrong position. I know I inserted the harness next to the gasket inbetween the block and intake runner. Maybe I should have placed the glow plug harness above the intake runner and on top thus the glow plug harness would be first then intake runner then gasket then block.(Some of my terminology may be wrong....but hopefully you understand). I am wondering if I cannot get a good seal because the glow plug harness attachment won't allow the intake runner far enough down on the gasket?

What do you think?

Also, clarification....I will unclip all fuel lines....but is it common practice to completely remove fuel lines when taking the intake manifold off?
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1987 300D (277,000)
1995 E300 Diesel (122,000)
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  #4  
Old 12-23-2005, 03:49 PM
BusyBenz
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The intake manifolds on these 603 engines are not always flat....mine leaks around #1 and 2.

It's hard to get a good turn on many of the hex bolts in order to torque properly, but chiefly the aluminum manifold may be in need of being milled in order to make a proper seal.

use a known straight edge such as a wide aluminum yard stick and see if there is a gap between ports....it should be flat all the way across from #1 to #6.

I glued 120 grit sand paper down on the deck of my delta unisaw table saw deck and moved the manifold back and forth until it was flat then cleaned up each port and used a new gasket.....no more black oozing leaks!

Last edited by BusyBenz; 12-23-2005 at 03:55 PM.
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  #5  
Old 12-23-2005, 06:56 PM
bfd bfd is offline
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Location: Houston, Tx
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The glow plug wiring harness does indeed attatch to the intake manifold using the manifold bolts. The attatchment holes for the harness rest on top of the intake manifold. If you have replaced the glow plug harness such that it is in contact with the gasket then you will not have good seal between the intake manifold and the head. You may have damaged the gasket in doing so. Remove the intake manifold again, inspect the gasket and replace (in the correct position this time) if it is damaged.
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  #6  
Old 12-23-2005, 07:05 PM
bfd bfd is offline
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Quote:
Originally Posted by bfd
Remove the intake manifold again, inspect the gasket and replace (in the correct position this time) if it is damaged.
Of course, I meant put the glow plug harness in the correct location

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