|
|
|
|
|
#1
05-04-2002, 12:03 AM
|
|||
|
|||
|
rough idle on 300SD
My '84 300SD has a rough idle, but runs fine going down the road. I had my mechanic do a pressure check on the head/engine and he found the exhaust valve on #2 is leaking. Everything else is good but at 1000 RPM's it runs rough. 5000 miles ago I had a timing chain go, but did not do a valve job because I was told that the valves and head were in good shape(machine shop). My engine stripped the crank and cam gears and bent the valve cover and broke the cam towers when the chain broke. I have been told it should have broke the cam and sometimes they break pistons or rods. I still get good on the road mileage 25-29 and it starts with no problem. It does not use any oil and I just changed all the oils and filters. Any ideas what happened and WHY???? I think it is a burnt valve, but why?? It was timed according to MB spec. and I watched it done. Thanks.
Chapp
__________________
1983 300SD 343K everyday car 1983 300SD 285K from junk yard-tooks parts from deer car- runs great. Brothers car. 1984 300SD parts car-Hit deer 1979 300D 175K non-turbo "Doctor" 1979 300d parts car 
|
|
#2
05-04-2002, 05:50 AM
|
|||
|
|||
|
TECH HELP-burnt valve on 300SD
I was hoping for an answer...I did a search for "rough idle" and got a lot of useful info, but none addressing WHY this would happen. I see a lot of posts after mine with replies...but none to me????I know this subject is covered a lot...but mine problem is different I think, this car has never run rough in 45,000 miles...until now.
Chapp
__________________
1983 300SD 343K everyday car 1983 300SD 285K from junk yard-tooks parts from deer car- runs great. Brothers car. 1984 300SD parts car-Hit deer 1979 300D 175K non-turbo "Doctor" 1979 300d parts car
|
|
#4
05-06-2002, 09:18 PM
|
|||
|
|||
|
I find it hard to believe that you didn't bend a valve in there somewhere. Jumping two teeth on the chain is enough to cause valve and piston impact. The valve may not have seated quite right on the seat after your mishap, and consequently burned at this area.
I would not be surprised if you don't have other valve damage that hasn't yet shown iteself. Recommendation is to pull the head and have it completely rebuilt to insure that all parts are in working order. This will also give you an opportunity to inspect the piston tops. I had this happen to me in a VW diesel once. The valves still "closed" the cylinder, but were still damaged, as were the pistons. That engine never ran correctly again. You are lucky.
|
|
#5
05-06-2002, 11:15 PM
|
|||
|
|||
|
Machine shop
The car ran flawlessly the first 5000 miles...it was timed acorrding to the CD I got from MB. The head went to a machine shop and I was told no damage..and it ran for 5000 mi. better than it had the first 40K I had it. I had the valves adjusted after 2000 mi. and they were fine. He ran a complete leak-down test and # 2 with hissing air out of exhaust pipe. No other cyd. showed any leakage. Why would a valve work great for so long then fail?? When the head was off, the pistons were inspected and the distance each was traveled were the same. No air leaked into the engine during the test...only the tail pipe. But all said.. I am sure there is bad exhaust valve on #2 and I drive over 100 miles aday and get 27-28 miles a gallon....It starts fine, and runs great after you get past the idle. The head will off soon and will let all you fine gentleman know what we found. Thanks!!!!
Chapp
__________________
1983 300SD 343K everyday car 1983 300SD 285K from junk yard-tooks parts from deer car- runs great. Brothers car. 1984 300SD parts car-Hit deer 1979 300D 175K non-turbo "Doctor" 1979 300d parts car
|
|
#6
05-07-2002, 01:39 AM
|
||||
|
||||
|
If it were my car I would adjust the valves again, just to make sure.
When were your injectors last cleaner and/or replaced? Have you ever adjusted your pump rack idle adjuster? Are your engine mounts OK.
|
 |
| Bookmarks |
|
|
Linear Mode
