Damaged camshaft bearings

[DavidA]

Hello, Looking for advice please. Low oil pressure light was flickering when warm. Replaced oil pump and crankshaft bearings, which were not too bad and pump working well. But did not cure the problem. Removed camshaft and discovered the bearings were not good (picture attached). Hoping replacing these will cure it but doubtful as I don’t know the cause of the damage. There was a short while before this happened the thermostats were dodgy and may have been running hot but uncertain of this or if it could have even caused this.

Has anyone seen this before in cam bearings?

Tractor is a new holland tm150 and has done 12500 hours but anyone experienced i have talked to has never seen or heard of this at any amount of hours. Also all cam followers have been checked and good.

Any ideas would be greatly appreciated

thanks.

 

[forblue]

At that hours you should have checked crank journal wear even if not scored wear would have taken place those shells are typical of oil pressure loss so again before fitting new ones check for wear with mic, you must remember crank and cam bearing depend on oil pressure to keep journals from touching by a film of oil and if that fails by loss of pressure and or dirty oil then the soft metal on the inner part of bearing will start to melt protecting the journal.

 

[farmgineer]

Looks like "galling" or adhesive wear. Its where metal on metal contact causes the softer material to basically melt and weld itself to the harder material. This then creates an abrasive action back on the softer material and the problem gets worse, usually quickly.
As has been said, the oil pressure in that journal must have been low to allow some contact between the two surfaces, leading to this.
I'd be looking to strip the lot and check everything over again. Sorry to be the bearer of bad news, but once you've done that it should be good for another 12500 hours

 

[f0ster]

what was the oil pickup strainer like, they can get clogged with carbon residue from the oil, starving the system

 

[Abacus]

At 12.500 hours it is getting close to the end of its serves life specially if a lot of the time has been spent at hi rpm like pumping slurry or road work it would be worth checking the rocker shaft oil feed if it was a Perkins the oil comes up to the camshaft then on to the rockers if the rocker feed is leaking it can drop the oil preacher in the camshaft I hope this makes sense

 

[DavidA]

Thank you i never gave wear on crank journals much thought , I didn’t have it out at all but visually what i saw of it looked good but I am no mechanic.

 

[DavidA]

All cam shells had a bit of damage, middle ones not so much. It is reassembled and on the tractor I would have liked to try it before i look in to it again.

The pickup strainer was clean and there was very little carbon build up anywhere inside the bottom of the engine. The pickup pipe is a bit of poor looking design bit, very flimsily shoves in to the bottom of the pump.

I dont know what the past history of the tractor i got it a few thousand hours ago, i did a check before I dismantled the second time by running the engine with the rocker cover off. I couldn’t see anything wrong but i have little experience on this. I would say there was quite a lot of oil coming up and out where its needed and a few drips where they rock on the shaft.

Thanks everyone for the feedback

 

[fermerboy]

I had a 7840 with well worn camshaft bearing shells, not as bad as that just showing the change in colour. it went a big end which is why I was into it anyway.

I changed them all and on another I have done since too, both times got away with a 10 thou grind on the big end bearings but a polish on the mains, they have to be run pretty bad and long for the mains to be rubbished.

As for Abacus theory that its getting to the end of its life at 12500hrs, complete nonsense, that Powerstars will do massive hours if well cared for using good oil changed regularly, not hard to find 20k hours plus examples.
Correct about checking the head carefully, there could be a loss of oil getting to the rockers due to wear elsewhere.

 

[Abacus]

seeing it look s good up top I would check the crank for wear you have a lack of oil preacher with a new pump can only be excessive wear or a folty preacher reles valve. Engines running at hi rpm all day every day don't often get to hi hours one's on grenral work not a problem its all about the number of times it has gone round not the hours and serveing has a big influence have a chat with timik

 

[Lakesdigger]

Takes very little oil pressure to knock light off so don't assume when light is off all is good could still be poor pressure. Could be relief valve or oil pick up. Pipe doesn't need to be blocked but could be drawing air through bad seal or even a crack. Best to fit a gauge on somewhere to check pressure.

 

[Right-arm fast]

Looks like low oil pressure to me??

 

[DavidA]

I have now had it running since the new cam shells but no difference or maybe even worse as the oil light faintly came on at 5 bars on the dash bar graph? I was told each bar is around 5 psi.
Our 7840 will run as low as 3 bars on graph with no problem.
I was also told that even if the big end crank journals were slightly worn with putting new shells in would have rectified the problem for a while at least.
The pressure relief valve was the first thing i checked, then a new pressure switch.
The oil pickup pipe was checked over again and a new oring in pump where pickup fits in to it.

I am out of ideas and loosing the will with it, i will probably take the head off and check the gasket next but wont likely find anything wrong in there.

Thanks for everyones interest and suggestions.

 

[Lofty1984]

@cosmagedon

 

[Mur Huwcun]

Have you actually stuck a gauge on it?

 

[DavidA]

I don't have a gauge, i could get someone to check it. I suppose it would rule out any fault with both old and new pressure switches and wiring.
I would have to check it against another tractor but i was told it should be around 20psi at idle and 50psi running speed?

 

[Bloders]

id get a gauge, they not expensive and certainly much cheaper than stipping anything else back down to investigate.

 

[DavidA]

Ok thanks

 

[Abacus]

had this with a Perkins check the mane journals and check the crank with a set of Verners they art round when worn I still think it is time for a rebilled have a chat with timik I think they do ford and if not still very knowable

 

[fermerboy]

I have a set of gauge and adaptors off ebay for £15, dead handy, maybe not super accurate as they are likely Chinese but will give you a fair guide. I've had the light switch turn dud before and freaked me out a bit on a good low hours engine but the gauge I borrowed showed oil pressure ok, new switch job sorted.
I wouldnt start a rebuilt engine without using gauge piped on, last one I run for a couple of days with gauge cable tied up to cab so I could watch it.
Not sure on the TM but I think one of the pressure switches on the backend can be swapped for engine oil pressure switch on a 40 series, handy to check out if its dud maybe.
Gauge it first, diagnose from there.

 

[startinghandle]

I have not read all comments so I could have missed something... did you renew camshaft??