Non Landy - Turbo Diesel Issue

[roverrescue]

!!!!APOLOGIES FOR LONG POST!!!!!

Well last nights red hunting trip was ruined because the mates boat engine decided to let us down... The boat is a 9m cabin platey and its powered by a
Volvo Penta Duoprop Sterndrive.

The engine is a straight 6 dieso with raw water to coolant exchanger. It has an inline injection pump, coolant & oil cooled turbo as big as a dinner plate, no intake charge intercooler. It develops approx 240hp (but not at the moment).

The obvious visual problem. The turbo "dump pipe" and exhaust is cooled by the raw water as it leaves the water/ coolant exchange unit, this then runs down the exhuast and exits the leg. Where the raw water enters the exhaust there is obvious corrosion and a lovely little water spout. Not enough to sink the boat but not a good sign.

The expensive problem. The engine will normally run to 3900rpm WOT, cruise is at 3500rpm where it will sit at say 16knots (load dependant). Last night once we cleared the leads and opened the taps the old girl was only making 2500rpm and the engine note was definately lacking that turbo whine we all love.

I checked the linkages and the linkage is going to the injection pump stops when pushed to WOT.
In nuetral I could rev the engine out to 3500 (moving the linkage by hand) and it sounded smooth (but loud!!!) all the way up, but no high pitched turbo whine.

Would it be a fair assumption that the engine and fuel pump is making rpm when no load is on (ie nuetral) but once load is applied, a non functioning (read corroded impellor wheel / housing) turbo means that the engine is not getting enough air to make rpm.

I will pull the "dump pipe" tonight and start hunting, but just throwing it out to the turbo diesel gurus for other diagnostic theories.

Im hoping I can get the snail off without pulling the engine... the weather is coming good and the mothership is needed!!!!


regards,
Steve

[Tank]

Remove the air intake pipe from the turbo and see if you can spin the compressor blades, if not you have a siezed turbo, while the pipe's off check it hasn't delaminated inside, Regards Frank.

[Lucus]

Might i suggest a fresh set of fuel filters and a boost check with a decent boost gauge before you dive into removing the turbo?

If your filters are blocked you wil still reach hi idle fine but wont be able supply the fuel required to generate enough boost reach full load rpm.

[roverrescue]

thankyou and thankyou...

I had thought the fuel supply may cause an issue at load. I guess you need fuel to ge the turbo tospin to make noise....

The exhaust housing will need to come off to fix the leak, so i will be able to check both the impellor, hopefully without removing anything major. Pull the intake to turbo and check compressor as well.

Where is the best location to tap for boost, anywhere along the inlet manifold?

S

[Lucus]

anywhere on the inlet manifold is fine. Being a volvo i would be surprissed if there isnt a boost tap provided on the outlet of the turbo. Is the turbo free floating or does it have a waste gate installed. If its gated you can tee into the boost sense line for the gate.

I would be sur****ed if the turbine wheel is corroded. If the wheel has been corroded for some time you would hear it as a high pitched whine, or you would hear the bang when the wheel/shaft let go. Of course this would be accompanied by the usual symptoms of a failed turbo (ie bulk smoke)

Its a shame the boats not in WA i just happen to know a experienced heavy duty mechanic thats just started his own business........ (me....... :) )

[roverrescue]

Thanks Lucus,
sounds like I may have someone to bounce things off! Maybe you need to do a late season Cape trip!!!!

Will have a look if the turbo is gated?

I do have manuals for the old girl so should be able to find boost values but ball park about 10psi at high idle????

The engine has been run but not in the water under load since a big trip up north in february where we did 300nm in a week. Apart from the small leak from the exhaust housing she ran like a dream all week. Last night was the first time its been in the drink since february. Maybe stale dieso or clogged filters is the problem.

At some stage the donk will have to come out as the sump has a good coating of ferrous oxide molecules holding hands...
The new shed has been designed with a gantry crane that will make pulling the engine an easy affair. But with the good weather just coming on we dont really want to pull an engine till march april if we can help it!

thanks again, ill get onto this arvo

Steve

[roverrescue]

followup on findings.

Turbo is non wastgated.

Elbow/ mixer needs replacement, nothing but rust.
Turbine was pretty well seized but will now turn with some interference to exhuast housing walls.

Waiting on rebuild vs exchange pricing.

"Bring Out Another Thousand"

S