OM602 rough idle only after 30 secs of running?
 

Hi All,

First post I am based in UK and been reading through a couple of old posts I wonder if anyone can put finger on my issue.

Vehicle is OM602 powered Hymer motor home having covered 80k miles and was running rough on purchase straight from cold start and throwing smoke from exhaust.

So far:

Failed to start -

4 glow plugs found to be faulty - 2 with hard short - full set of 5 put in.

Injectors pulled and sent away for rebuild all 5 reconditioned - injector co. said all low on pressure and 2 a little suspect but not too bad.

Prior to injectors it ran rough all the time worse until it warmed up buy rough straight from startup.

Since injectors it will now run good for 30 seconds then reverts to poor running and smoke from exhaust - tickover remains poor even when warm.

Video below - any suggestions please? please bear in mind I am not mechanically minded. Both vids are from same cold start one from engine and one facing exhaust.

https://www.youtube.com/watch?v=HHX2SI3hIik

https://www.youtube.com/watch?v=kptiffYM2sA

Thank you :-)

Anyone? Cracked injectors today ...seems to be problem is isolated to cylinder 1.

Time for a compression test?

There is a known head gasket issue between cylinder 1 and the oil passage on 60x engines, and early ones have some head crack problems, I avree that a compression test is a good idea.

IMO, it runs too nice when first started up to be compression. I would pick air is getting in the injector somehow. Known to be wrong though :)

Possibly a poor spray pattern due to worn delivery valve spring on cylinder #1.

Test:

a) Disconnect one hard line completely,
b) Attach a spare hard line and a spare injector to the delivery valve and look at the spray pattern as you crank the engine with glow plug harness disconnected.
c) Reconnect the original hard line,
d) Repeat steps a through c for the other four hard lines

You should get the same spray pattern from each of the delivery valves if the IP is working properly as you are using the same injector each time.

Have you set your valves lately ?
On small engines when the valves expand a tiny bit it can cause the engine to quit... but once cooled again... starts up perfectly...

You have a head gasket problem either loosing coolant or oil! The first 30 seconds are when the glow plugs aid compression to establish ignition.

Wow, thanks guys gives me something to go at - I have booked in for a cylinder leakage test Friday.

I also ordered a purge kit - I guess prob wont work but will give it a shot :-)

Alec - makes sense for testing IP - I'll think how to get a spare injector line - the cut over lever is missing so maybe i find both at breakers?

Leathermang - I had someone tell me that the valves/ tappets were hydrolic and no adjustment possible? Ill follow you other links now - thank you.

Should have mentioned it ha sbeen fitted with an aftermarket turbo - the engine is originally NA and a UK company specalised in fittinmg turbo's to many of these engines. In europe we dont have alder units and no overboost protection which i have seen mentioned on you tube - also have no ideo how extra fuel get in for the turbo ....not sure if relevant - but thought id post it any way. :-)

Thank you all for wisdom - really appreciate it :-)

Could also be as the heating effect of the first cylinders glow plug is dropping off the cylinder starts to miss. Personally I would want a compression check of that cylinder. This also would be the time to check for any oily condition in there as well.

Or just hook up a temporary constant voltage supply to the first glow plug. If the cylinder does not start to act up thirty seconds after startup is an easier way to establish it is not fuel supply related.

That engine probably was worked hard in that type of vehicle. When we usually put an aftermarket turbo on a non turbo engine it is not to increase overall constant power basically. Yet in that type of vehicle it was probably used as such. For example if I put an after market turbo on one of my old 240ds with the four cylinder 616 engine. I would only use the turbo for increased acceleration. The normal output of that engine can sustain the power needed in most applications. It may help a little on hills as well but in general I would not be really constantly forcing the engine into a service it was not designed for.

Good morning All
RoscoePeko - did you get to the bottom of your issue....


just as you had done - i have had my injectors over hauled, new nozzels and i believe the pop stuff to be all set correctly...

after starting i also get the exact same issue, 30 sec of starting smooth almost like a new engine, then 30 secs into running lovely I start to hear the engine running rough look at exhaust, starts blowing smoke.


stop engine, start up and shes fine again for 30 secs or so....

stays at rough idle even when engine is warm

weird or what....




any chance of letting me know what your issue was in the end..


thanks
richard

Find the idle solenoid on the back of your IP. Try disconnecting it and see if there’s a change. If so, you may have a problem with the EDS system.

hi thanks for the reply


no EDS on my old girl...

hi guys



after reading alot of other posts regarding rough idle
lots of people mention GlowPlugs can cause this. however my old girl fires up perfectly after a short blast on the glow plugs.


can glow plugs really cause rough idle

seems to me the rough idle starts when the GP relay switches off....??


1. smooth starting, no smoke

2. runs fine for 30 secs then rough idle and smoke




thoughts please

Did you do a compression test?

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?