Damaged camshaft bearings

[DavidA]

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.

I looked on ebay plenty but don’t really say if they have a 1/4npt thread adaptor. Will just take a chance on one. There is a pressure switch the same on hydraulic pump i could try.
Do you remember if you had oil light flicker when your big end went on 78? Or remember any pressure readings you got?

 

[DavidA]

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

I didn’t replace cam as looked good, and was a good fit in new shells.

 

[fermerboy]

I looked on ebay plenty but don’t really say if they have a 1/4npt thread adaptor. Will just take a chance on one. There is a pressure switch the same on hydraulic pump i could try.
Do you remember if you had oil light flicker when your big end went on 78? Or remember any pressure readings you got?

The kit I have is similar to this but isnt quick connect to the pipe.

https://www.ebay.co.uk/itm/184738493023?hash=item2b0345b25f:g:i~EAAOSwE9FgZWYB

My 7840 is a dual power so no bar graph on the dash, only the warning light.

I was full chat carting straw from about 15miles away, when I heard the note change a little, thought it was a rattling mudguard or panel, backed off the revs to about 2100 and she ran perfect 6-7miles to straw, loaded the load no bother, set off home loaded and again, full chat, a slight knock, came home about 2000rpms and only on the last 3miles(uphill) did it get worse till I was down to maybe 1500. Even at that point I thought it was a rocker/tappet/valve or something, just wasnt't a heavy knock. Never had an oil light flicker or any clue that it was major. Number 1 big end had picked up (furthest from the pump) rest were a bit worn but not excessively. She had just over 12000 very, very hard hours on her then.
Ended up getting the big ends ground 10thou, mains just needed a polish.
I felt the cam bearings were real worn so changed them, they are cheap when you are in that far, very surprised that not every bearing is fitted or drilled, think its only 5 out of 7.
New rings, hone bores, oil pump, and full seal and gasket set, back to work.
Think I put pics on here somewhere, might still have them.
Never had a oil pressure reading then but did when I put her together, can't honestly remember the readings, maybe 50-60psi cold, 25-30psi hot.
Should really put gauge on and see what it is now with another 4000hrs.

 

[cosmagedon]

@cosmagedon

I've just rebuilt one in a TM190 but generally engines aren't my specialty!

I've not read every comment but I was taught that oil pressure is made at the crank, I would be making sure the big ends and mains are all perfect, stick a gauge on in different places to see what oil pressure you've got and dont always trust the dash.

 

[Timbo]

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?

Buy a gauge and some fittings. They're cheaper than wrecking the motor.

 

[fermerboy]

I would echo Timbos answer, buy/borrow a gauge, a cheapy off Ebay is good enough if you aren't using it much, the light and the bar graph on the dash is not enough to tell if you have problems.

Might just be a duff sensor, or a stuck relief valve.
Just read the posts again, you say the light is flickering when the bar graph is reading ok, something doesn't add up right, sounds like a dud, or a blockage to it.

Was the engine clean inside when you were in?
By that I mean solid gummed up crud in strainer, oil ways etc, if its had crap oil in it previously or poor changes that could be the problem.
I've never changed shells in situ and always blow the hell out of the oil ways to make sure they are clean, not so easy if its not apart.

They are good strong motors, and there are no hidden tricks to them, oil pressure is simple, good oil, by a strong pump, and not too much clearance on the moving bits for the pressure to escape.
Shop manual tells you all the acceptable wear, and what to check.

 

[Lincsman]

May be wrong, but have some engines a switch for the oil pressure light and another sensor for the oil pressure?

 

[Mur Huwcun]

May be wrong, but have some engines a switch for the oil pressure light and another sensor for the oil pressure?

Yes, two sensors on the powerstars, single wire one for the light on side of block while the bar graph works off the two or three wires sensor

 

[DavidA]

Thanks for all the reply's, have a ebay oil gauge ordered.
It was very clean inside no build up of any kind, all oil ways i could see in were spotless.
Will see what readings i get with oil pressure.

 

[DavidA]

I would echo Timbos answer, buy/borrow a gauge, a cheapy off Ebay is good enough if you aren't using it much, the light and the bar graph on the dash is not enough to tell if you have problems.

Might just be a duff sensor, or a stuck relief valve.
Just read the posts again, you say the light is flickering when the bar graph is reading ok, something doesn't add up right, sounds like a dud, or a blockage to it.

Was the engine clean inside when you were in?
By that I mean solid gummed up crud in strainer, oil ways etc, if its had crap oil in it previously or poor changes that could be the problem.
I've never changed shells in situ and always blow the hell out of the oil ways to make sure they are clean, not so easy if its not apart.

They are good strong motors, and there are no hidden tricks to them, oil pressure is simple, good oil, by a strong pump, and not too much clearance on the moving bits for the pressure to escape.
Shop manual tells you all the acceptable wear, and what to check.

Hello as you mentioned in this post. The new oil pressure sensor was dud. It was the first thing that got replaced at the start of the problem months ago now! It was a cheap branded one, been fine with them in the past.

I bought the oil pressure tester gauge you left link to on ebay, i was getting 30psi hot at idle 800rpm. Thought it was a false reading, got it checked against another gauge and another tractor and was almost the same.
Used the hydraulic pump pressure switch like you mentioned as the same, which is only a few month old, and no flickering light on anymore.
The dud new pressure switch says 12-19psi on it, and it was no better than original one with light coming on at around the same pressure. The working one in now is a genuine nh part one rated the same says 10-19psi on it.

Next job front hub bearings slack.

 

[fermerboy]

Hello as you mentioned in this post. The new oil pressure sensor was dud. It was the first thing that got replaced at the start of the problem months ago now! It was a cheap branded one, been fine with them in the past.

I bought the oil pressure tester gauge you left link to on ebay, i was getting 30psi hot at idle 800rpm. Thought it was a false reading, got it checked against another gauge and another tractor and was almost the same.
Used the hydraulic pump pressure switch like you mentioned as the same, which is only a few month old, and no flickering light on anymore.
The dud new pressure switch says 12-19psi on it, and it was no better than original one with light coming on at around the same pressure. The working one in now is a genuine nh part one rated the same says 10-19psi on it.

Next job front hub bearings slack.

Nice one, thats a result!!!
Shame you had all that stress and work, but at least you know shes good now!!