How often should IP be timed? - PeachParts Mercedes-Benz Forum

WANT '71 280SEL · #1 06-09-2004, 08:17 PM

I am speaking of my '79 300SD. How often should the procedure be done?
Thanks
David

tjohn · #2 06-10-2004, 08:13 AM

Not at all, unless you have a particular problem that you need to solve. An out of time IP will cause additional smoking, and ore severe cases can cost you mpg or even some power. If your timing chain is stretched, you can retime the IP to bring it back into spec. Once its there, unless your smoke increases (and you ruled out the easier causes, like a plugged air filter), your mpg drops, or you have other complaints, I'd leave it alone.

leathermang · #3 06-10-2004, 08:18 AM

If you keep your fuel mileage stats all the time you could use that to give you an idea as to when to start looking at stuff... but that includes valve adjustment, etc...
and the figures on oil useage can point to needing to check things like leaks, valve stem seals, etc
But if everything is hunkydory then you don't need to be messing with it...

WANT '71 280SEL · #4 06-10-2004, 09:40 AM

Well, I figured the chain has probably stretched some in 205k miles, and I'll bet it's never been done before, would that be a reason to do it. I get 24 mpg, tops.
Thanks
David

leathermang · #5 06-10-2004, 10:27 AM

The procedures you are talking about are not particularly hard to do... or cost much in the way of tools.... at that many miles it would be great to check it out....many people get 3 miles per gallon better mileage than you do....

Wasuchi · #6 06-10-2004, 11:48 AM

This is an SD that he's talking about though so I'd bet that 24mpg is pretty much the average for a car that big.

leathermang · #7 06-10-2004, 12:03 PM

Well, he sounded like he was looking for support for justifying checking it... I think at 200k miles is a good time...

Rick Miley · #8 06-10-2004, 12:08 PM

Uh oh, Greg. You've stepped in it now!

Benzcrusher · #9 06-10-2004, 12:31 PM

I've been thinking about fooling with the IP in my 300D. It has a 617.950 ('79 SD) motor with unknow miles. It runs great except it is "dead" off the line, even with the car in neutral it takes a second to rev up, worse when it's cold. I got use to it but it is dangerous trying to get into traffic with the AC on. Once it hits about 2000 rpm it just zooms but it takes 3 or 4 seconds to go from 750RPM to 2000RPM.......

boneheaddoctor · #10 06-10-2004, 02:26 PM

Quote:

Originally posted by WANT '71 280SEL
Well, I figured the chain has probably stretched some in 205k miles, and I'll bet it's never been done before, would that be a reason to do it. I get 24 mpg, tops.
Thanks
David

I have an indicated and I believe accurate 116,654 miles on My '79 300 SD and I seem to get a fairly consistant 24 mpg.

psdsteve · #11 06-10-2004, 04:23 PM

I have 197K on my 82SD and routinely get 28+ mpg with 90% highway driving.

I don't have any acceleration problems either I haven't tested it but it might outaccelerate my Bronco.

Stephen

tjohn · #12 06-10-2004, 08:32 PM

Quote:

Originally posted by WANT '71 280SEL
Well, I figured the chain has probably stretched some in 205k miles, and I'll bet it's never been done before, would that be a reason to do it. I get 24 mpg, tops.
Thanks
David

Well, 24 mpg is kinda average mileage for OM 617 SD's. On summer fuel I get 24-25 around town and more like 27-28 out on the highway. If you want to do this job, some people recommend doing your engine mounts at the same time. The theory is that you have to jack up the engine to do the mounts. Once jacked up it's supposed to be easier to get to the nut on the back of the IP that must be loosened to adjust it. All I know is getting that nut loose was probably the suckiest job I've done on my car. Having said that, adjusting the timing did seem to push me over the hump to finally getting better than 22 mpg.