Engine not Reving?

[G.Mac]

Alright there folks,

It appears that we may have a problem with our engine as it only revs to 1700 rpm instead of 2600rpm.
My brother Andy conacted Mermaid and their initial guess was that the wrong fuel filters had been fitted so he bought and replaced the 3 fuel filters on the engine but to no avail. The engine appears to be getting full throttle so that leaves us thinking its either the Turbo or the Fuel pump that may be goosed, both expensive items unfortunately.
I was wondering if anyone who had more experience of these engines and their quirks may wish to comment on our problem and steer us in the right direction?

Oh yea the engine is the 204hp turbo 4

Graeme

[doggypaddle]

I am not familiar with this particular engine, but assuming its a standard non electronic diesel, here is what i would check first after changing filters, although you probably allready know/done most of thisdoes it smoke a lot under way?black smoke, too rich, lack of air or overfuelling,blue smoke, engine oil, suspect turbo seals or rings/valve guides.white smoke diesel, extreme overfuelling or low compression, bad injector, usually causes obvious missfire.does it rev up to 2600 off load?(if not broken govenor spring is not unheared of or even the stop adjuster come loose not allowing full travel on the cable)If its does rev off load and its just down on power under way, check if the injector pump has a compensator. this is a diaphragm that increases fueling with boost pressure, if this gets split then you wont get the fuel to match the boost also check the pipe from the manifold to the compensator.A dodgy lift pump can also lower the fuel delivery on bosh ve pumps.also you could pull the intake hose off the turbo and check its free to spin, and not got too much play, also check none of the turbo hoses have blown off loosing boost.another possibility of aparent lack of power could be the hull cruddy?cant think of anything else at the moment.

[m chappelow]

once had problems with an underpowered diesel and fault was as doggy paddle just said it was the engine stop lever and cable that was not getting full travel ,hence the stop was at half cock when in running position ,it would stop ok but would not give full fuel when running fast , also how about wrong grade of engine oil could be too thick though it may not turn over fast or start, does the turbo have an oil feed pipe thats blocked and the turbos siesed up.

[doggypaddle]

if the wrong grade of oil was causing this it would have to be seriously thick.
eg gear oil 90 weight, that said hot 90wt gear oil is very thin as its a monograde, so its unlikely to be the problem. of course if a cold engine was revved with gear oil in it it would do serious damage before the thick oil got where its needed. also the ep additives in gear oil eat babbit bearing material, really not good in an engine.

[G.Mac]

Cheers for the feedback folks.

It does not help being a couple of thousand miles from home, but I got an email from my brother today saying that he has been in communications with Mermaid and they reccon its now the fuel pump seeing as the filters did not cure the problem
So Andy ordered a fuel pump and has fitted it and the revs have increased to 2100rpm but the turbo does not feel as if it is spooling properly. When he got the boat out the water this was confirmed by the black residue on the arse end of the boat.
Next step is to remove the turbo, strip it and clean and see what happens. Upon initial inspection there seemed to be a reasonable coating of oily residue on the inlet to the cold side so it may be gunged up. He was saying that the turbo looks similar to an old Garrett T2 unit, so if it is it will be easy and reasonably cheap to get new guts and or modify the turbo, so he will be busy counting and measuring blades over the next couple of days.
On another note he also ordered new seals for the oil cooler as it was weeping, but when he went to fit them he found that the housing is corroded so back off to Mermaid to order a new oil cooler too!!!


Oh the joys of an old boat that has not been run for some time!!!!

Will keep you updated

Graeme

[doggypaddle]

the turbo wont stop it revving to the correct governed speed off load.i would say the throttle stop on the injector pump should be wound out until the engine revs up to around 2850-2900 rpm off load. this will allow for govenor run out, so maximum full load rpm will be around 2-300 rpm lower.If the turbo isnt siezed then its unlikely to be the problem, if it has a wastegate that could be stuck open?you could have a chicken and egg situation here ....the turbo wont create any boost if there is insuffecient fuel delivery, and if it has a compensator diaphragm, the injector pump wont start to deliver extra fuel until there is some boost building up!if i was close i would come and have a look! as nos will confirm i am quite good at getting diesels to fly!

[G.Mac]

Many thanks,

I have emailed him all of your info with a link to this thread.
I will be home Saturday night so that should make things easier as I wond be dealing with 2nd hand information so will be able to post exactly what we have been trying.

All the best

Graeme

[Pete7]

If the turbo has been leaking oil then the air cooler is going to be a right mess. Good news is that it all comes apart and fits nicely in SWMBO dishwasher

Their is a wiring block on the FIP, if he puts 24 volts across it then the rack will fully open and give 100%

Pete

[G.Mac]

Screwed out the screw on the govenor? as pointed to by the red arrow



by one and a half turns and now the engine revs to about 2500 rpm under load and the turbo is now spooling up.

When you put the stick right down she will rev to 2000rpm, then drop back down to 1800 rpm before creeping up to 2100rpm where the turbo starts to spool. She will then rise to 2400rpm and slowly creep to 2500 rpm

This is only good if your going in a strait line with no waves as you cannot "jag" the throttle as the response is piss poor to say the least which is no use for any sort of wave work.

The exhaust hose decided to blow its self apart so further runs were aborted and the boat recovered.

Mermaid have sugested checking the valve clearences so will be doing that once Andy gets home from the rigs.

getting better but still not right

Graeme

[Channel Ribs]

Originally Posted by G.Mac

The exhaust hose decided to blow its self apart so further runs were aborted and the boat recovered.

Sounds like you have a nice winter project coming up, I am sure you will have a sound engine by the end of the process.

[doggypaddle]

That screw you pointed to is the rack stop, this effectively adjusts the fuel delivery, when adjusting by allowing the fuel rack to open futher. this will not affect the maximum governed RPM of the engine, however if fueling is very lean obviously the load will stop the engine revving up to governed speed.

Really you need to check the valve clearences, though in my opinion its unlikley to be a problem, and intake exhaust for blockages then assuming ther fuel filters are clear and there are no other problems with leaking pipework make sure the engine can reach ~300 rpm more than the expected max on load speed on the throttle stop screw, then start fiddling around with this screw until you just get a little whif of black smoke under aceleration.
It will also be worth checking if there is a compensator device on the pump, and if it works, this will increace fuel with boost.(i cant see one)
diesels without a compensator can smoke fairly heavily when accelerating while the turbo plays catch up. it should be clean once the turbo spools up.

If you are unsure if you have over fuelled fit an exhaust gas pyrometer. do a google on EGTs I would also fit a boost gauge so i could see whats going on.
When pumps come from calibration they can be wrong, yours could be set to fuel a non turbo for example!
I am unsure why your rpm dips, maybe because of the hull shape and bite the prop has? or some anomaly with the fuel delivery, i think it requires more fiddling

[G.Mac]

Cheers for that, im not the one doing the fiddling thats Andy my brother I just do the steering (Im a decky afterall!)

the prop has a fair bite, this is a pic from when we first got the boat



and hull profile



Hull has been cleaned since these photos

T the posn where it is has been fiddled to just now theres alot of black reek when accelerating but once the turbo spools it runs clear. There is a boost gauge fitted, once the turbo spools it hits a max of half a bar then once the boat is up to speed it drops to 0.4 of a bar

As you say more fiddling required!!!

New exhaust hose is on order so will be removing the old exhaust and checking for any blockages due to growth etc, the valve clearances will be checked Fri / Sat depending on weather as boat is outside (I think Mermaid quoted 0.18 for inlets and exhausts) and turbo will be removed for inspection and overhaul (got a rebuild kit on the way). We have also got a full set of water and boost hoses so these will be changed out also.
Charge cooler has already been taken off, cleaned and painted

[doggypaddle]

I wouldnt touch the turbo yet, its unlikely problem unless its obviously lunched if you visibly inspect the compressor and turbine, if you disturb it it needs balancing or the result could be catastrophic.
I think you found the problem....if the boost is falling once the boat is up to speed then its because the fuel is reducing. this is probably because the no load speed is set too low.
the phenomenon is called govenor run out, if the no load speed of the engine is set to say 2800RPM which would be in the right area for the engine the fuel rack will stay fully open until around 2300-2400 then it starts to shut off.
so if you want the full load speed of the engine to be 2800 you may need to adjust the throttle stop to allow a bit more movement.
theres two screws on the throttle arm one for tickover and one for max rpm.
try a tweak here, it may get those last few hundered rpm you need to get the extra speed.
still at a loss why the rpms dip though!
It sounds like he govenor RPM and the Rack stop were both set a bit cautiously.
If you have black smoke under aceleration, and .5 bar boost then that may well be all its got to give in terms of aceleration without risking high EGTs and melted turbine blades.
Its worth checking what the boost is meant to be, if its low then it could be the turbo, does it have a wastegate that could be sticking open and reducing boost?

[doggypaddle]

One other thing are you sure its a 204HP? i have been looking at mermaid engines on the website, and i recognise the engine as a ford tractor engine,
I am familiar with the 4 and 6 cylinder versions, and the six turbos arent even 200HP i thought the 4 cylinders were about 150hp. Unless they run a lot more boost than the six?

[G.Mac]

Cheers for all the great info, will read a couple more times to digest.

http://www.mermaid-marine.co.uk/PDF/...TurboFour3.pdf

We bought the boat through Babcock Disposals advertised as 204HP, whilst chatting to mermaid they told us that the last of the Turbo 4 units for the MOD were uprated to 200BHP with uprated internals. Im going up to the boat tomorrow to get some serial nos from the turbo and engine and will be able to confirm (or deny) what power rating the boat is.
Will also be talking to Turbo technics to see if they can offer advice on a Hybrid turbo to aid spool if we hit a dead end.

On initial sniffing about the turbo there apears to be no wastegate fitted
they arnt the best pics, but will try get some more whilst up at the boat tomorrow





Many thanks

Graeme

[Pete7]

Grame, for reference Old Spice with a 200 hp Mermaid used to get over 1 bar of boost from the turbo at speed. Turbo was noticable from 1800 revs and smoked really quite badly until then. Max revs was 2800 in gear with 21 and 22 inch props and light loaded. The P22 manual is here is you want it:

http://www.polar-ribs.co.uk/


Pete

[doggypaddle]

Hi,
as there is no wastegate on the turbo,or a compensator or the pump then you will have to put up with smoke before the turbo spools up.
If extra fuel on the screw you already played with dont improve things and increace boost, then, as pete 7 suggests youre low on boost it may be worth checking the exhaust for blockages and the turbo for damage and its the correct unit.
did you spill time the engine when you changed the pump? if the timing isnt spot on that wont help.
its still worth trying more fuel on that screw, it may make the turbo spool quicker and actually reduce the smoke once it gets going.
IMO the turbo should be creating boost from quite low rpm.

as you say a hybrid turbo may improve bottom end but may jigger the top end, a wastegate is the way to go with a smaller turbo to reduce lag.

or fit a nice 6 cylinder yanmar

[G.Mac]

Screw the 6cyl yanmar
V8 Tigershark diesel 400HP - 948lbs torque
http://allmarinediesel.com/Tigershark%20Page.htm

Will update you all at the weekend once we have been back up to the boat

Graeme

[Pete7]

In addition to the exhaust hose, I would have a look at the route air takes from the turbo to finally entering the clys. Since the Mermaid has an intercooler and several pipes any one of these could either leak or have a pacial blockage. The ali parts are easy enough to take part and stuff in a dishwasher to get clean

Pete

[Dirk Diggler]

Originally Posted by G.Mac

V8 Tigershark diesel 400HP - 948lbs torque

They really are a piece of crap. A pal of mine had one installed by the local agent in his boat, but it didn't perform as expected, been back to marine diesel in Sweden a few times, and they can't make it work. Last time back they put it on the dyno, and admitted it was only making 230 ish hp! They're unable to sort it, and having spoken to numerous people who've tried other motors from them, it seems to be a common problem.