I have a leak where the head portion of the thermostat bypass line connects to the head. It is an approx 1.25" dia aluminium pipe about 4" long. Talking with 3 dealers and 8 indy's in the local area no one has ever seen a leak in this spot. They also do not know how it is connected. 2 of 9 guess that it has pipe threads and is screwed into the head. The others either won't venture a guess or refer to the fiche and say start looking for a new head. Any experience or ideas for solving this leak is seriously sought, just changed the head gasket, really would like to solve this without pulling the head again!

Sure it's not the small, not-so-fun-to-replace hose that's about 2.5" long. Could also be a loose clamp(s) or simpy old hose in need of replacement.

It could be leaking from the hose to the pipe/head area.

Removal and installation of the metal pipe which sticks out of the M103 block is described in the MB engine manual and CD. It is not screwed into the block, but is fixed in place with LocTite.

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Neil Chandler

Thanks Neil,
You mentioned finding it in the CD. I looked in the engine section of the 126 series sold by MBUSA and couldn't find anything. Is that the CD your using?

Now if I can work it out with out damaging it. Have not used locktite as a glue before. How long would you recommend to let it dry?

If it is an engine only CD, would you mind emailing me the directions. kjuul@widomaker.com

paraphrasing would work if the file gets too big to send.

Thanks again, nice to finally have an answer.

91300SEL: That was my first thought too. The hose is in good shape, new 6 months ago with the water pump change. Thought I forgot to tighten the clamp after doing the head gasket but it was tight. Believe me, I wish it was that easy!

I went through this just last week while solving an overheating problem on my 190. The books and Cd are at home, let me look up the exact instructions for you tonight.

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Neil Chandler

That would be great! As I mentioned in the original post this is a very uncommon failure. Will post a response for the archives when I get it finished.

Ken, I have job no. 20-2110 as a pdf file. Can attachments be sent to the list, or does it strip them out? If it does, send me your email and I will send it direct. My emai is : chandler6@slb.com
A summary of the instructions follows:

With the water pump already removed, the connecting pipe is removed by applying pressure to the side with a punch to loosen it in the cylinder head. it is then pulled out with pliers. The new pipe is coated with Loctite 270 high strength sealant (MB 002 989 93 71 10), and then knocked in to the hole until it seats with a plastic hammer.

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Neil Chandler