timing chain cover removed. gasket broke. help!
 

Hi guys,

I went to mechanic today for him to remove my timing chain cover to install new guides. One of inner guide was broken and missing. During removal mechanic damaged oil pan gasket and left gasket where timing cover meets the head. Is it possible to put silicone sealer on on gaskets to prevent leaks? Otherwise he says I need to replace whole head gasket. What can be done?

Thank you.
Car is 92 500sel.

I'm assuming he removed the oil pan to remove the FOD from the old rails.

I'm assuming he also removed a valve cover to acess the timing chain.

As a rule, you should not need any kind of sealer thats not part of the gasket (some gaskets come with a sealer which is dry to the touch, but seals under heat/pressure (ie installation))

If the mechanic is even contemplating reusing a head gasket, he is an idiot and I would never trust another car to him if my life depended on it. If he's refering to a valve cover gasket, thats a different story. Sometimes you can reuse a valve cover gasket, but rule of thumb is when in doubt replace it. I'm replacing a valve cover gasket on my car tonight becuase I suspect it may be the cuase of a leak and it has a flat spot in it where it shouldn't. It's less than $10.

Head gaskets typically run for $75 to $100 depending on the car
Valve cover gaskets typically run $5 to $20 depending
Oil pan gaskets $10 - $30

Check on Fastlane for your specific car and you can get an idea. For what the mechanic is charging you per hour, it's probably cheaper for you to have him do it right and replace the gasket rather than pay him for his time to Jerry-rig an old gasket with silicon. (Gaskets are meant to be replaced from time to time, seldom reused)

Again, I'd be skeptical of him needing to pull a head for new guides... perhaps there's more difference between the 119 and 117 engine than I know of. Hopefully another member with some 119 experiance can chime in.


Good luck

Well, the manual for a 117 claims that if care is taken, the head gasket can be preserved when removing the front cover. Obviously, this didn't happen here although the engine is a little different. I wouldn't trust anything but a gasket in this high-heat area, I think silicone would simply vaporize. Yeah, I know that this is a lot of work/$$$$...

You should be ok patching the oil pan gasket with "blue hylomar", the cylinder head gasket area you are talking about is not subject to combustion pressure and you might get away with sealing it with the same stuff so long as you make sure the gasket ends are butted tightly together during reassembly.
If it leaks tell your "mechanic" to get it fixed FOC as he broke it.!!!!
Geo.

potential leak at head/valve cover/case joint
 

MBZ did a 'fantastic' job using CAD to design this multi-surface joint--beautifully precise on paper. Unfortunately, when you have gaskets that must seal across multiple surfaces--it becomes extremely difficult to remove any one of those surfaces and replace it without some kind of damage. Hell--it is IMPOSSIBLE to keep this joint on the V-12's from leaking with all new gaskets, much less removing one part and reinstalling.


I think it is unfair to ask the mechanic to do the head gasket replacement free. That probability is inherent in that work. Sometimes you can clean the joint well and use the MBZ special sealant with good results.Sometimes it leaks. I would not pull the head--I would clean carefully, completely, lastly with rubbing alcohol, and use the MBZ part # stuff specifically called for and not worry.

Thanks for suggestions, guys.
Shop owner provided me with space in shop where I can work on car myself. I will reassemble car myself. And I will replace upper oil pan gasket because I am still very skeptical that it will not leak even when sealed with sealent. Top front head gasket will have to be sealed. No point to pull heads to replace it. One corner of head gasket is broken badly. Only metal insert is left. Sealing material is missing. So perhaphs using a lot of sealent/gasket maker will prevent leaks. Now I just need to find that sealer "blue hylomar" or speacial MBZ sealer.
Can I buy "blue hylomar" in Autozone?
Thank you for help.

"Blue hylomar" should be readily available from auto accessory stores, at least it is in UK. It's what Rolls Royce used to use on their car engines.
Geo.