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?