I'm not a happy bunny - knackered D9

[kashurst]

finally replaced the drive coupling, boat taken out for a really good run everything sounds fine. After @ 40 minutes port engine (one that has had the work done) stops. Check down below assuming must have missed something when putting it all back together. No - everything looks fine, engine starts immmediately but doesn't sound right. Switch off back to marina on one engine again. Listen to engine back in marine - strange noise and inconsistent running. For a few seconds every now and then it sounds OK but then runs rough again. Sounds like the noise is coming from the top of the engine but hard to tell. Local Volvo agent has been and had a look today - Vodia box talks to engine - seems there is a cam shaft sensor error, but passes the so called compression test on all cylinders and switching each injector off in turn doesn't change the sound. Next step is to start disassembling the top of the engine. Worst case I've got a melted piston, best case something loose on the top of the cylinder head. Do D9s have sleeved cylinders? Any clues?

 

[benjenbav]

A slightly sticky valve, maybe?

 

[jfm]

Keep us informed on diagnosis. We've had a melted piston D9 on here before, belonging to a poster. I was driving (gently) at the time. 500hp version, around 400 hours, full service history, one owner from new, 4 years old approx. It took an age but Volvo did contribute substantially to the massive repair cost.

The D9 engine has wet liner cylinders. Replaceable valve seats. 4 valves per cyl, single camshaft driving all the valves and the unit injectors. Good luck

 

[[2068]]

Melted piston seems unlikely if compression is okay ... cylinder liners are replaceable on a D9, but still not cheap to rebuild.
Hopefully it's just a minor (ish) top-end issue of some kind, also worth checking obvious things like fuel filters, then pumps.

 

[andy59]

Sorry to hear that Kashurst , hope its something simple / easy to fix , good luck .

 

[Andyroonot]

What is the fault code for the cam shaft sensor? Has that aspect of the problem been addressed? D9 requires both cam & flywheel position sensors for proper running, but can & will start if one is faulty or even unplugged; it will likely be rough though as it is working out the timing just using the spaces on the flywheel. So it could be the answer unless you feel it is more than just a noise of it running a bit lumpy?

 

[burgundyben]

What is the fault code for the cam shaft sensor? Has that aspect of the problem been addressed? D9 requires both cam & flywheel position sensors for proper running, but can & will start if one is faulty or even unplugged; it will likely be rough though as it is working out the timing just using the spaces on the flywheel. So it could be the answer unless you feel it is more than just a noise of it running a bit lumpy?

If it is the cam sensor then the ECU won't know where the engine is in the 4 stoke cycle, hence it might run like a bag of spanners.

Rubbish time of year for this to happen, hopefully quick and not to £££ to fix.

 

[henryf]

From your description this sounds like a sensor fault or something in that area. I would be incredibly surprised if you had a melted piston.

Melted pistons don't just heal themselves for a while to let the engine run properly. Electronic sensors / wiring may well do though.

I wouldn't be too worried at this stage. Also melted pistons will produce vast clouds of smoke and possibly even run on as the engine oil gets burnt.

The compression check will probably have been a simple case of shutting off one injector at a time then seeing if the engine revs drop off. It you had a compression problem the revs wouldn't drop off significantly for that cylinder because it wasn't doing any work (due to the lack of compression). Overall wear across al cylinders can't be detected using this method.

Henry

 

[kashurst]

Back in Spain again with the duff d9. So far vodka box has demonstrated injectors are all working and compression is fine. However the Volvo tech explained that to maintain a smooth idle the amount of fuel injected varies from cylinder to cylinder depending on the sensor inputs - can sensor crank etc. It seems my engine is modulating the idle amount more than usual to compensate for something. We have swapped various sensors and vodka confirmed all good. Today I wired up the starter so I can turn the engine over with no combustion so we can see\hear any funny noises. It all sounds fine until I stop it when as it comes to a halt there is a distinct "clack clack" sound. The sound definitely comes from the timing gears. We have taken off the cam cover and inlet manifold to hear better and visually check the valve train (all perfect and very clean especially engine inlet tracts). I have been turning the engine over by hand and it feels OK. We put a tiny camera down the timing gears and every thing looks good - no missing bits. The only bit we cant check is the camshaft harmonic damper. Yes camshaft damper. Can anyone shed any light on camshaft damper failure symptoms

 

[[2068]]

If this was a car with a timing chain, I'd be suspecting that a camshaft had "jumped" a tooth.
... I'd be checking for play in any of the timing gear bearings, check the timing itself, and that the harmonic damper isn't distintegrating or about to fall off.

 

[vas]

vodka tool?

I cannot help at all, but can surely be a good thing that compression is fine, you're now in a different league (which should be much cheaper I'd expect!)
OTOH, sensors, cabling, ECUs, etc is never an easy thing to debug, so good luck.

cheers

V.

 

[volvopaul]

vodka tool?

I cannot help at all, but can surely be a good thing that compression is fine, you're now in a different league (which should be much cheaper I'd expect!)
OTOH, sensors, cabling, ECUs, etc is never an easy thing to debug, so good luck.

cheers

V.

Kevin means. VODIA tool, it's volvos diagnostic tool.

Kevin if nothing is wrong from the vodia and no sensors are at fault along with compressions being ok and no broken teeth on the timing I'm wondering if the last tech has done something wrong when he fitted the flywheel damper, this all sounds really strange that this latest fault has appeared after works being done.

Did they take the flywheel off?

If the front damper has failed that's an easy fix as engine is facing the nice way on your V drive install.

 

[kashurst]

Hi Paul no flywheel wasn't removed neither the crankshaft damper- I suspect the camshaft damper at the top of the engine. Must admit I have never encountered one before. Re vodka tool sorry tesco hudl spelling correct for vodia

 

[Latestarter1]

Hi Paul no flywheel wasn't removed neither the crankshaft damper- I suspect the camshaft damper at the top of the engine. Must admit I have never encountered one before. Re vodka tool sorry tesco hudl spelling correct for vodia

Kevin I have no specific knowledge of Volvo D9 design details however....

Camshaft has no inherent torsional activity. Overhead camshaft engines with gear driven camshafts are a designers worst nightmare. Straightforward you would think, gears train has to transmit drive from the torsionally active crankshaft to the cam, however there is the cylinder head block interface which gets in the way. The design of OHC gear train has to a accommodate a means to allow for a tolerance stack up in the head/block and in addition margin has to be added to allow for block to be decked in the event of gasket failure and the block face becoming torched.

Cat, Cummins and Detroit all have various monkey motion gears to take account of the issue however they are noisy, Volvo used the Cummins ISX 15 litre in certain export models of the FH truck, however Volvo hated the noise created by the ISX front end scissor gear arrangement.

European designers are far more noise aware in their designs than those from the U.S, preferring to locate cam drives at the rear of the engine, IVECO FPT go as far as removing the service tolerance completely in their Cursor OHC engines creating a potentially throw away motor in the event of a serious head gasket failure marking the block deck.

As I said at the beginning, not sure how Volvo accommodate head/block tolerance differences and the device they use to prevent torsionals instigated by the crankshaft making the gears argue too much, however I can see that failure of this monkey motion device could create you condition.

 

[kashurst]

Thanks for the replies. Removed the camshaft damper today and span the engine on the starter. When it stops there is quite a clatter from the timing gears. The harmonic damper is disguising the problem. Bugger, some more checks to do tomorrow before blocking up the engine to start dismantelling it. I think one of the timing gear bearings has failed. Just for LS, Volvo handle the head gasket issus with a gear on an adjustable carrier so you set the clearance with a 0.1mm feeler gauge and then nip it up. I hoped this may have come loose or moved but i m not having any luck at the moment.

 

[lynall]

At work all the old volvo trucks are going thank my lucky stars! and on the desk is a whole heap of pukka volvo workshop manuals for the 9 litre engine so will have a look tonight as Im now curious, thats of course assuming its the same?

 

[Latestarter1]

I really ought to stay away from Volvo motors but hooked now! Just found an SAE paper submitted by Volvo as to rear gear train design of Volvo D9/13/16 motors and the use of camshaft dampers to obtain low noise characteristics.

Coming from the U.S so will be here next next week.

Need to get a life, however can never stop asking 'why'

 

[henryf]

Is there a timing chain tensioner? Possibly a hydraulic tensioner which is slackening off as the oil pressure drops?

Either way this does sound like a fixable issue.

Henry

 

[lynall]

I looked in the manual, it cant be hard to adjust as its covered in just half an A4 page and that includes pics!
Measure using dti cam gear backlash, if incorrect slacken carrier bolts and set up using feeler gauge and recheck backlash.
Very specific on the width of the sealant bead needed.

 

[Latestarter1]

Is there a timing chain tensioner? Possibly a hydraulic tensioner which is slackening off as the oil pressure drops?

Either way this does sound like a fixable issue.

Henry

Henry,

D9 is a heavy duty engine, to drive overhead camshaft with unit injectors with a chain whilst solving the head block tolerance issues as well as noise at a stroke is not a solution.

Heavy duty engines require gear drive to provide the required levels of power transmission and durability, chains are, with just one historical exception the province of LDA (light Duty Automotive) engines.