E420 cylinder crack

I own a 1994 E420 that is in the middle of a head gasket job.Upon dissasembly I discovered that the left front cylinder head bolt hole(#8 in the tightening sequence)of the left cylinder has two cracks that go all the way through the block.They both start at the surface and go down about 1.5 inches.I have the later open-deck head.I had it welded (there was evidence that it had been welded in this exact place once before) and resurfaced to spec,installed the head,and torqued it down.The #8 bolt took the required torque and did not feel stripped.Needless to say that did not fix the problem.I tore it apart today with the intention of installing a heli-coil but stopped when I noticed that the recent weld has recracked in the same place.So the big question is can it be repaired and how?


Thank you.

markE420,

Sorry to hear out about the crack.

Just wondering, how many miles on your E420? I didn't think the M119 motors needed any major top end work until into the high 100k mile range.

It sounds like you are not the original owner since you were unaware of the previous head repair.

Thanks!

[stevebfl]

Can you send a picture. I don't understand the crack. Aluminum welds with a stronger result than cast iron. Is the bolt being torqued with liquid in the hole?

Yes I used oil,three stage tightening sequence,55 NM + 90 degrees + 90 degrees. My guess would be that a previous mechanic got distracted and went 90 degrees too far. I will try to borrow a digital camera and take some pictures.

[Benzmac]

No, what Steve means is as follows.

If you install head bolts without drying out the holes you can end up with a hydraulic lock in the bolt hole that can damage the block. This is most likely what broke it. You will need to send him a pic so he can look at it.

Steve has a degree in metalurgy (sp?)

[Machnumber2]

They can make engine blocks out of aluminum!?! I did not know this

[stevebfl]

Yes...they do. I wish I had time for the whole story as I was finishing my Metallugical Engineering degree at the same time I was working for GM who was building a car named Vega. HypoEutectic alloyed Al -SiO2 cast blocks.

[JCE]

Our 1963 Olds f85 had a gem of a 215 CID v8 with Aluminum heads, block, and intake manifold. It later was used in Morgans and Rovers, I believe.

[engatwork]

me correctly you are correct. Buick used that aluminum engine (I think) and then GM sold it to Rover where it was used up until a few years ago. It may still be used.
Jim

'85 300D - cast iron head and block
'95 E320
'97 CRV

[chowpit]

Bummer in regard to the crack.
I owuld like to see a pick also. I haven't had the opportunity to tear one down as they were still fairly new when I was working on MB.

[stevebfl]

Mark,

I received your email and replied but my reply was returned as address unknown (or some such). I can take most image formats to answer your question.

[stevebfl]

I looked at the pictures (good pictures) and my previous warning seems to be the culprit. It appears that the head bolt was tightened on a hole with a liquid in it.

If I am right about that, it means that the structural integrety of the area is not the failure. This can be important depending on the level of fix that you want.

The cracks were not welded properly. The outside weld had no penetration. The top surface must have been notched and welded over and remachined down. There appears to be many porosity bubbles in the surface. This can be caused by all kinds of problems. The proper repair probably would be to notch out the whole area and rebuild with weld. I don't do that level of aluminum welding on blocks, mainly because of the machining requirements. This amount of repair would require the motor being out of the car, I would imagine. I only know one person that can do that kind of work. he is in Orlando FL.

The significance of the cause of the crack leaves the possibility for a partial repair. If the structure of the area is sound an insert could be put into what is left and the cracks should be no worry as they aren't in sealing areas. All that is necessary from that hole is that a head bolt be able to get proper torque on the head.

[Edited by Webmaster on 04-10-2001 at 06:25 PM]

[engatwork]

through Steve
It looks like a very poor weld repair job.
I wonder though - is that not part of the water jacket that we are seeing? Would not an insert allow water to leak out?
Based on years of weld repairs around black liquor recovery boilers it is very important that you get a "full penetration" weld to obtain a proper repair. Steve knows.

Jim
'85 300D - no check engine light here
'95 E320
'97 CRV

[Machnumber2]

Nice photos!
Yeah it looks like a lousy weld job, but it also looks like a very difficult place to do a weld

[Michael]

What caused you to go into the motor in the first place, and how many miles on your car?

Best of luck with your repair