You haven't told us what year and model you're dealing with. If you have a 1990+ year model, you have an afterglow style relay. If you have injection or compression issues, the afterglow will mask your mechanical problems until it times out and quits the afterglow. Then suddenly the car starts running like crap. The pre-90s cars didn't have afterglow and they'll start and run just fine. Afterglow was added to make cold starting quieter, and assist the engine in sub-freezing temps.

If your injectors are old, it's time to consider a nozzle replacement or rebuild. Checking compression would be a good idea, low compression will lead to poor starting and/or running when the engine is cold.

Sorry guys

I was following on from the 2 videos that Risoepeko uploaded at the beginning of this post as the symptoms are exactly what he posted
The videos show exactly my issues

Mine is a 1993 OM602
Non turbo
I have just had the injectors refurbished new nozzles I dont know anything about what pressure pop has been set on them. As that I guess is why I paid the man that knows more than me, cleaned all chambers before replacing new injector seals
I also took the opportunity to replace all 5 Glowplugs.

I haven’t done a compression test as yet
Was hoping someone would know what roscoepeko’s solution was

The OP's last login was October 2016. I doubt he'll be posting his resolution anytime soon.

Compression Test this was taken cold



*1 380
*2 380
*3 380
*4 385
*5 420


so looking at pump timing now....:confused:

Cold compression test with these numbers? It cannot be right. Even a hot engine may or may not have these numbers. I normally get less then 250 or much less with stone cold engine. Check whether there is any gas escaping from the vent hole at the left back of the valve cover when rough idle HAPPENS. If there is then I suspect the compression of cylinder(s) of your engine is shot.

Why can't it be right? My SDL had cold compression numbers in the 360-380 range. 250 is very poor on a 60x series, even for stone-cold.


The little hole in the back of the valve cover is only a breather for the original PCV puck that's riveted in the valve cover. When the diaphragm goes (and they do), they'll leak smoke/vapor if there is anything above a 0PSI gradient between the inside of the engine and the atmosphere. For reference, the inside of the engine will always be at a higher pressure than atmospheric....even on a brand new engine.

Whatever you say if you think you know best.

Do your own research. Spouting nonsense and getting upset when someone calls you out on it doesn't help this forum or the OP troubleshoot his problem.

Really, I get upset? If you say so.

Normal pressure for OM603: 26-32 bar 377-464 psi. This is the spec for HOT engine. My experience with cold engine is that you would not get numbers like 380, not even close. I rest my case as I have bigger fish to fry.


BTW, the vent hole is very important and don't ever plug it. The pressure inside the valve cover is LESS than atmospheric for a good engine with good turbo. There should be no smoke coming out at the vent hole.

The engine being discussed is NA engine.

Your reactions and replies seem to back up my claims.

Hot compression will definitely be higher than cold compression. But you shouldn't be seeing 100+ PSI increase with a hot engine vs a cold one. There are plenty of people posting plenty of measurements on plenty of engines on plenty of forums that it only takes a few seconds to search for what other people have on their own cold engines. 350-380PSI on a cold engine is a routine number for the 60x and even the 61x series engines.

The vent hole is the atmospheric balance port for the spring loaded diaphragm puck on the breather system. The diaphragm puck is designed to close if the turbo pulls a vacuum on the valve cover. The balance port is there to reference against atmospheric pressure. At idle, the turbo is not spooled. It is actually a restriction in the intake path, not a pump moving air like it is when spooled up. Ideally the crankcase should not be under pressure or vacuum in a perfect world. This is not a perfect world. When the diaphragm ruptures and fails, you can get smoke wisping out of that balance port. It doesn't mean anything about the state of the engine. You can check that by doing the cap bounce test. On a 60x, the cap shouldn't move.

Again, do your research.

Guys Guys.......




these compression readings are indeed correct @ Cold, as I had sent my injectors back to get checked after they were refurbed with new nozzles etc.


i actually did the comporession test twice



these were the readings after allowing 3/4 turns




Injectors have come back and been told nothing wrong surpirse surpirse,

Your compression numbers are fine. Were the injectors just pop tested, or was the pattern checked as well? It would be worth your time to check chain stretch and cam/IP vs. crank timing. If the chain has stretched, your cam and IP may be slightly retarded and can certainly lead to late injection and smoke/stumbling at idle. It's worth pulling the valve cover and checking anyway, some of the late 602's have been documented to have a softer than usual camshaft sprocket that can wear to pointed teeth (affecting timing).

Hi Thanks again for your reply


great ok ill be checking the chain for stretch and may take a look at adjusting pump and as you say may be worth popping the rocker cover off and take a look at sprocket


will report back



thanks

Did u get to the bottom of the problem?