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Perkins D3.152 Oil Pressure Fluctuations


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I came across this post on TractorByNet and I have a remarkably similar problem:

 
Quote

 

Date: Sep 2013 
Location: Gloucester uk
Default Perkins D3.152 as fitted to MF135 - oil pressure
Hi
I hope it isok to post here, I have bought a D3.152 to put into a canal boat in the uk. It has been rebuilt with new pistons, liners, crank regrind, bearings, oil pump etc. 
The problem that I have is that after a hard run of around an hour, the idle oil pressure drops to 15psi - it is 60psi when cold. Temps are fine and the engine has been out of the boat once ( no easy job) and another new Perkins oil pump fitted, but no better.
Could anyone advise me what the hot idle oil pressure should be, the manual says 30psi when running fast, but I can't find any mention of idle pressure anywhere. 
Would very much appreciatevany advice from owners of this engine.
Thanks
Richard

 

I wonder whether Richardf59 ever solved his issue satisfactorily. I have a D3.152 dating back to pre-1992 (the age of the boat), which I can only guess was taken from an MF135 tractor or generator and marinised for installation into a narrowboat. We have had it for two years without much problem, except for some clogged fuel filters, but broke down in March this year and we had to have the engine removed and rebuilt after finding one piston was oval in the cylinder; all bearings, liners and pistons replaced, and new oil pump fitted. In fact the engine had to come out twice, because during the first re-installation something metallic smashed up the crown of one of the new pistons. Anyway, when we finally had everything back in order she ran beautifully; from cold the idling oil pressure was about 40-50 psi. However, I have found that an hour or so after getting up to temperature (75 C, constant) the oil pressure gauge can fluctuate rapidly from 10-60 psi, even at normal cruising speeds, often mimicking the tone of the engine (revs fluctuating?), and to maintain good pressure we have to push the revs up higher than normal. At idle and tick-over the pressure reads a constant 20 psi, but I am concerned that this could also be bottoming out on the gauge range and simply a reading error. The sensor and gauge are electric, so I shall be swapping with a new one and also testing with a hydraulic pressure gauge next week. At normal cruise speeds on some long days (6-8 hours running) the oil pressure fluctuates around 30 psi and above, so the engineer who rebuilt it says it is within normal operating parameters, but this doesn't fill me with confidence for the long term. I use a 15W40 oil and changed the oil and filters after 50 hours after re-installation, which made no difference. I have no rev counter, just gauges for temperature, oil pressure and battery charge. Any thoughts/suggestions welcome.
 
 
 
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Possible problem with the oil pressure bypass valve sticking open, though I can't see why that should kick in an hour or so after engine has warmed up, so perhaps not? 

 

When I had a failed spring on the bypass of a Perkins P3 many decades ago, the symptom was it couldn't better much over 20 psi, even when starting cold, so I doubt it's that, but just possible spring is good but valve sticking somehow? 

 

I suspect not, but something to bear in mind, unless experts say it can't be that. 

 

 

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Our D3.152 oil pressure reading behaves in a similar way.

The only spec. for oil pressure I can find is 30psi at 1000rpm ....

We have both a gauge and pressure switch on our engine and slowing down after a good run the oil warning light flickers for a short while when the revs drop right down; but the gauge shows about 10-15 psi . A slight speed up and let the revs drop back and the light goes off!

We do tend to run our engine quite slowly compared to how they would have been run for "real work" and  I do notice that  hire boats using this engine tend to be run much faster than ours especially  at tickover.  ( 1400rpm will move us at 7mph on the Great Ouse so we only use a slightly fast tickover on the canals )

For what its worth the oil pressure is being read,  I think, from the camshaft feed and that has a cut out in the shaft which causes pulses in pressure switch readings but  I assume the (electrical) gauge sender must damp these pulses .

Our engine was purchased  "marinised".  I think from a sold-off ex ministry pump. We did have considerable oil dilution from leaking seals on the fuel injection pump which caused a real drop in oil pressure.

Edited by JohnB
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I'm not so concerned about the drop in pressure over a long day, although I wonder whether changing to a different oil might help (currently 15W40), but the wild variation of the gauge, particularly after an engine rebuild when the oil pump and PRV were supposedly replaced, does seem strange. The bouncing needle of the gauge was common before the rebuild at idle, but usually stabilised at mid-revs and rock solid at faster speeds. Now the situation is constant 20psi pressures at idle (although I have my doubts this is a true reading), fluctuations at mid-revs, with some improvement at higher revs; the same pressure sender and gauge were installed before and after the rebuild (soon to be changed).

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Firstly, Back in the day the oil of choice for these Perkins types was usually a straight 30 although I doubt that is has any bearing on your problem.  To me this is more than likely a gauge issue. I've had similar on a old Dorman where the gauge seemed to have a mind of its own. Personally I would change it for an oil filled gauge which are far better at damping than the old fashioned ones.

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3 hours ago, steamraiser2 said:

Firstly, Back in the day the oil of choice for these Perkins types was usually a straight 30 although I doubt that is has any bearing on your problem.  To me this is more than likely a gauge issue. I've had similar on a old Dorman where the gauge seemed to have a mind of its own. Personally I would change it for an oil filled gauge which are far better at damping than the old fashioned ones.

I suspect you are on the right tack but if its an electric gauge I would suspect the sender before gauge.

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Memories from Richardf59 (From TractorByNet):

Hi

I remember the issue we had with the Perkins - it was a really stressful time as we had initially had the engine replaced with a like for like Kelvin P4 which proved to be worse than the old one (bought å–ªefurbished from Marine Power Services? and then having made the big decision to get rid of it - the Perkins was a nightmare to get right. We never did get to the bottom of it, but they took it away and rebuilt it again - I always reckoned that they put the wrong size bearings in it initially. I always found Canalworld a good place to ask questions like this. Wildly varying oil pressure sounds like a blockage somewhere or a pick up issue in the sump, maybe an oil pump issue. Once fixed, mine never ran less than 45psi The boat is sold now (nb Marcellus), but the Perkins was a great engine - although I never really got the exhaust running clean!
All the best with it. 
Cheers
Richardf59

 

I have the same experience with our engine not running clean; before and after the rebuild it tends to smoke more than most.
 

  • Greenie 1
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  • 2 weeks later...

We ran the boat through Chester yesterday. The new gauge and sender definitely give a damped fluctuation of the needle, however the same drop (and more) in pressure is still concerning me. At cold start it indicates 50 psi, falling to 40 psi when warmed up and running at normal cruise. After an hour of running at this speed it has dropped slightly, but when in idle/tickover the pressure fluctuates between 0-5 psi.

It suggests there may be some heat build-up in the oil, so it losses its viscosity, whilst the coolant is staying constant at 75C.

Edited by Binkie's Grandson
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Symptoms typical of:

 

Oil PRV jammed open

Worn oil pump

Worn bearings.

 

I don't know if the Perkins has an externally accessibly PRV but if it does that's the first thing to check. Do not pack or stretch the spring. Best get a new one if the old one is suspect.

 

If the PRV is internal then I fear its an engine out and sump off to investigate.

 

Sorry.

 

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6 minutes ago, Tony Brooks said:

Symptoms typical of:

 

Oil PRV jammed open

Worn oil pump

Worn bearings.

 

I don't know if the Perkins has an externally accessibly PRV but if it does that's the first thing to check. Do not pack or stretch the spring. Best get a new one if the old one is suspect.

 

If the PRV is internal then I fear its an engine out and sump off to investigate.

 

Sorry.

 

If a D3 is constructed like a P3, and I rather fear it is, then to get at the pressure relief valve is sadly likely to be an engine out and sump off job.

 

When I had a failed spring on the relief valve of a P3 many years ago, my memory is that whilst the engine had always exhibited good oil pressure, it would then not make more than 20psi, whether hot or cold, so it doesn't sound much like the symptom here.  But perhaps it's not a fully broken spring, but (say) maybe something that's got in and preventing full closure?

Also on my P3, even hot and at idle, the pressure was still good enough that it was considered OK to boat back from Central London to Hertfordshire before lifting the engine - certainly not down in the 0 to 5 psi range, which, if you have a new gauge ad its the same, would certainly be concerning me.

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Can we be absolutely clear. 

 

Once hot you have a good 40 psi indicated at normal cruising speed, but only zero to 5 psi at tick over? 

 

That sounds pretty unusual.  So, what kind of RPM are you doing when yo get say 20psi.  And what RPM for say 10 psi. 

 

I agree with Tony that if you have new matching gauge and sender that the zero to 5 sounds most unhealthy -, I'd not want to be running it at all at those numbers. 

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Alan that is absolutely typical of a PRV stuck open or anything else that allows sufficient oil to escape back to the sump so lowering the oil pressure. What it is not typical of is a partially blocked oil pump inlet strainer because if the strainer was blocked you would expect lower pressure when cold and revving.

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I may be clutching at straws, but could the fact that it is a newly rebuilt engine (~100 hours), running tight, be generating more friction and heat in the oil, so it loses its viscosity after a run. There is some improvement after a period at idle, presumably because the oil has a chance to cool, although the temp gauge doesn't show any increase on the normal 75C operating temperature.

 

When it was rebuilt the oil pump was replaced (at least according to the invoice!).

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20 hours ago, Tony Brooks said:

Alan that is absolutely typical of a PRV stuck open or anything else that allows sufficient oil to escape back to the sump so lowering the oil pressure. What it is not typical of is a partially blocked oil pump inlet strainer because if the strainer was blocked you would expect lower pressure when cold and revving.

 

7 minutes ago, alan_fincher said:

If you are getting 0 to 5 psi at idle hen it is hot, what psi are you getting at idle when it is cold?

How quickly does it move from one situation to the other?

 

 

 

2 minutes ago, Binkie's Grandson said:

40+ when it is cold. It takes about 15-20 minutes to get up to normal temperature, and pressures are still good at cruising and idle; the drop off seems to happen after an hour or so of cruising, although no perceptible change on the temperature gauge.

 

All I can say is that in no way aligns with my memory of experiences of a P3 engine I had back in the 1970s where the spring in the PRV broke.

 

If the engine can make over 40 psi at idle when cold, and hold it until it has run up to an hour, I'm struggling to believe the oil could then lose so much viscosity that it falls close to almost zero. I can't help thinking something else is at play.

On our engine with a completely broken spring it certainly continued to make an acceptable pressure at idle even when hot - I would not have carried on with it with 5psi or less on the gauge.  It also failed to reach anything like full oil pressure at running speed, whatever the temperature - I always assumed because the oil had a permanently easy path through the open PRV.

Anyway this is way outside my limited experience, so I fear I'm not helping much(!)

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59 minutes ago, Tony Brooks said:

Yours had a broken spring so it was always well open. When the PRV jambs open it is often only by a small amount so when the oil is viscous the pressure cab build up. In this case it could even be a weak spring rather than a jammed valve.

Yes, I agree mine was a fractured spring, and this could be a different PRV fault.

I'm interested though how you can explain the idle pressure taking round about a full hour to fall from a healthy 40psi plus to under 5 psi.

I would have thought if jammed partially open to the extent it can make 40psi at idle when cold, and still be at that after 15 to 20 minutes, it is unlikely that the change in viscosity of the oil could suddenly make it drop to close to zero at about a further three quarters of an hour later on.

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1 minute ago, alan_fincher said:

Yes, I agree mine was a fractured spring, and this could be a different PRV fault.

I'm interested though how you can explain the idle pressure taking round about a full hour to fall from a healthy 40psi plus to under 5 psi.

I would have thought if jammed partially open to the extent it can make 40psi at idle when cold, and still be at that after 15 to 20 minutes, it is unlikely that the change in viscosity of the oil could suddenly make it drop to close to zero at about a further three quarters of an hour later on.

I have seen a number of faulty PRVs over the years, mainly on the BMC 1.5 but the principle is the same. They can give those symptoms and we only have the OP's word for how long it takes to drop. Whatever is causing it the OP has almost ruled out a gauge problem, especially as if I remember correctly the original was a mechanical gauge, so it looks as if the sump will have to come off so hopefully we will find out then.

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1 minute ago, Tony Brooks said:

Whatever is causing it the OP has almost ruled out a gauge problem, especially as if I remember correctly the original was a mechanical gauge, so it looks as if the sump will have to come off so hopefully we will find out then.

Yes, I agree.

If two completely different gauges tell the same story, the problem seems to be real, and I think the engine will have to be lifted.

 

I'd want to do that soon, rather than ever running at idle with zero or close to zero on the gauge, or it could suddenly get hugely more expensive, I think.

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Binkies Grandson says that the engine was rebuilt. If there was any machining done like rebore there is a good chance that a tiny bit of metal swarf is trapped under the pressure relief valve holding it off its seat a little. If so perhaps a good flushing with flushing oil or a 50/50 mix of cheap engine oil and diesel fuel or paraffin, running the engine for 10 minutes or so then changing that oil for its normal oil, and changing the oil filter.

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