Detroit diesel mechanic recommendations ?

[mattysupra]

Hi, can anyone recommend a Detroit diesel mechanic who can "tune" my Detroit 92's ?

I'm getting a little black smoke when blipping the throttles at low revs, I understand the fuel ratio needs turning down a bit ?

And my main problem is that one engine has started to blue smoke on tickover . It's fine under load. It never used to blue smoke, I was using boat fine and turned off, next day I started and there is now blue smoke. Not sure if injector issue maybe ?

I'm near Worcester if there are any Detroit specialists around or willing to travel ?

Thanks.

 

[Divemaster1]

Ok ... having spoken a bit on these engines here in the past, I'll bite...

Is the engine in Worchester as well ... or in the boat somewhere else ??

Also are they V8 / V6 Naturals or Turbo engines ... and which rating .... how many hours .... and how do you use the boat?

I would not be too worried about the black smoke ... that is probably "just" carbon build-up, or a bit excessive fuel squirted in before turbo spins up... but a tune-up may be in order (but may not completely remove this).

How comfortable are you at wielding a spanner yourself ??

The blue smoke may be an injector sticking a bit (replacement or re-build of injector .... I'd go for a refurb one from Detroit at about £60 with exchange ... but you need to know which injector ... and what size ID)... There's a simple process to find out which one and just replace this one... then do a tune-up (about 3 - 4 hr per engine I'd hazard to guess..

On a more serious note, you could have a cylinder with damaged piston rings... in which case the work is a "bit more involved"... but once again relatively simple to identify which cylinder ... but much more $$ to repair...

So a bit more info required please, then we may be able of helping further...

Biggest DD outfit I know of in England is in East midlands I believe ... http://www.mitchells.co.uk/marine/ ....and they may be able of recommend an independent DD Mech...

 

[SpottyDog5]

Alf, you beat me to it, I was going to recommend Mitchells, not only were they very good at the work they did (sorting a fuel leak on the head) on my DD's but they stuck to the original quote even when they picked up an slightly chafed hose that only could been seen when they were into the job.
The guys they sent were "proper mechanics" not just box changers, not that you could really do that much on a DD.

 

[mattysupra]

Hi, thanks for the help so far.

They are -

Detroit 92's v6 single turbo 550 bhp. They was rebuilt by Mitchell's and serviced by them for previous owner. They have covered approx 100 hours. Every thing was replaced at rebuilt including turbos, injectors etc. receipt for engines on there own is over 30k but also had new gearboxes etc also. Basically everything mechanical is new or should I say at around 100 hours. O and fuel tanks was removed cleaned etc also.

I use the boat on the river and sea. One the river I only use one engine to try and keep load on them rather than just ticking over. At sea they get loaded up and I will cruise at 22 knots but will give short blasts a WOT for around 2 mins at a time every hour or so which sees speeds well in to the 30's .

When this engine started to let out blue smoke i was just locking out to sea. Was fine the day before. But as soon as I started it fresh the next day it started to smoke.

I still went out to sea and opened the engines up watching the smoke. The smoke cleared under load and the engines produced again normal top speed, I kept them open for longer tho to keep a eye on gauges and to see if any smoke but every thing was fine. I stop at marina to check oil rather than going to where I was originally going and in the lock the engine started pouring out blue smoke again.

Today I have noticed what looks like diesel bug / slime in one of the racer glass filters ?
The fuel system was fully cleaned and fuel filters changed only 6 weeks ago. I have done maybe 40 hours on these filters at sea. I also double dosed the system with diesel bug treatment 6 weeks ago and used all that fuel without issues.

Have I picked up dodgy fuel at last fill up maybe? ( filled up the day before the smoke started) ?

Ps, the boat is in Worcester .

 

[Divemaster1]

OK ... £30 K for a re-build of two V6's sounds like a proper factory rebuild ... including liners, pistons, rings, bearings etc., so all good in principle... but no guarantee of course...

If you have a single cylinder failure... such as a ignition failure as in injecting too much fuel and non-ignition (fuel being injected and subsequently being split between exhaust and scavenging ports) you should have a slight change between the two engines in vibration and sound.... You should see a slight fuel sheen on the water behind exhaust and some blue smoke... also if you spend a lot of time at idle/low rpm, you will have build-up of fuel in the lube oil (through airbox drains)... so you may have a failed injector if that is the case.

If you have a failed piston ring (relatively easy to detect in 30 min to one hour on these engines when you know where to look), then the case becomes an issue about questioning the re-build quality...

Irrespective, a "tune-up" will not resolve your blue smoke ... but may reduce black smoke and fuel economy...

 

[mattysupra]

Hi, Sorry for the delay getting back. I have been back to the boat this weekend. To bring you up to date, i did a diesel bug test and that has come back at zero. So the slime etc i can see must be from a previous issue. However its dead.

I would of reported back earlier but me PC died along with other issues !

So i have run the engines again and we have found -

No crankcase pressure, No pressure coming out the top either. However we have noticed the bad engine is rocking more that the other and started hunting up and down slightly. So with the help above which is greatly appreciated i hope it is a injector. On with my search to find someone to work on the engines for me!

Divemaster1 , do you have any pictures of whats inside the rocker covers please? I think i might be best trying to stop each injector injecting to find which cylinder is at fault?

Thanks again.

 

[Divemaster1]

.....

Divemaster1 , do you have any pictures of whats inside the rocker covers please? I think i might be best trying to stop each injector injecting to find which cylinder is at fault?

Thanks again.

Sure ,.....

This is a 71 series engine, but 71 and 92 share loads of parts, including injectors, so you should look similar...

to locate the injectors is easy ... that is the central rocker arm of three on each cylinder....

Start the engine up (wit rocker cover off) and let her idle... find yourself a large or broad screwdriver, put it on top of injector (careful with those rocker arms moving .... and also the turbo if you have removed the air intake ) and force down the injector spring down (prevent her from springing up again).... and hold injector down for a while.... if engine note changes, then injector is probably OK... (good to have someone watching to see if exhaust colour changes as well) ...... repeat process until you have done all injectors...

As you have a V engine, please only have one side exposed at the time (unless you safely can walk around engine and keep clear of the other cylinder bank rocker arms etc...)

Some more info on cylinder head removal etc., in he link below.

http://www.ybw.com/forums/showthread.php?376659

Good luck !

 

[mattysupra]

Thankyou, i will report back in a couple of weeks as im away so wont get chance to go to my boat.