W123 Head pipe replacement. - PeachParts Mercedes-Benz Forum

Renntag · #1 10-31-2011, 11:00 AM

There are a few small holes in the lower portion of the head pipe due to rust. I am planning to straight pipe the OM617 powered 300TD and have considered fabricating a head pipe. Roughly $30-40 in parts if the upper portion is still strong enough to weld to.

My question for this post is two part.

As I consider the value of my time compared to the cost of a replacement head pipe, has anyone found an alternate replacement?

Has anyone eliminated the flex joint in the head pipe? I have done this with success on some front drive race cars, and have never seen one on a rear drive car until owning this W123. I would imagine that as long as the motor mounts are good, this joint isnt critical.

Thoughts?

boneheaddoctor · #2 10-31-2011, 12:36 PM

You need that flex joint.....just look at the engine move at startup and shutdown and its self explanitory what going to happen if its not there. Besides....many other cars are built in such a manner that the exhast pipe to the manifold is spring loaded and allows a degree of movement. Hondas come to mind as my reference.

I'd get a replacement unless you were planning to custom fit a slightly larger diameter system to the rear bumper.

I replaced mine, last year. For me it wasn't worth the time and agrivation to fabricate one. When a new one bolts right up without issue.

Renntag · #3 10-31-2011, 04:03 PM

Thanks. But even with the rubber mounting of everything there is a fair amount of flex. Just because there is a flex pipe, doesnt mean it is critical. It could be overkill.

Either way, I am leaning toward just bolting on a replacement part and then cutting out the other boxes down stream. I dont feel it necessary to increase pipe diameter unless I was looking for an excessive amount of pipe echo.

Looking to see if anyone has found a cheap replacement.

supercub · #4 10-31-2011, 10:45 PM

Head pipes are cheap, autozone or *********.com.

vstech · #5 11-01-2011, 09:05 AM

I used a 16.00 flex connector 2" and welded it to the downpipe/collector. no issues, and simple (I have mig!)

Orv · #6 11-01-2011, 02:54 PM

Quote:

Originally Posted by Renntag

Thanks. But even with the rubber mounting of everything there is a fair amount of flex. Just because there is a flex pipe, doesnt mean it is critical. It could be overkill.

They made a couple million of these cars. If they'd saved $5 on each one by leaving out the flex pipe, they'd have made $10,000,000 more in profit. That makes me think if it's there, it's probably necessary.