MF TEA low compression

[MikeyMonster]

Hello
Ive a Massey Ferguson TEA28 (i think the 28 is the nz version of the more common 24 but im not sure). Anyhow it has low compression in cylinder 2.
90,50,90,90. I thought it might be a bad valve but it doesnt appear to be. Im wondering if anyone has any tips on working out if its the headgasket or the piston/rings?
Also can you replace the pistons on these by removing the oil pan and dropping the piston out from below?
Its a petrol by the way.
Ive never worked on a tractors or cars engine internally before although i can rebuild a two stroke outboard motor as easy as pie.
I appreciate any response
Mike

 

[Baby Grand]

It's been a while since I had any bad head gaskets, but I remember different symptoms, depending on where the gasket failed:
Blowing coolant into the oil, in which case the oil becomes milky looking.
Sucking coolant into the combustion chamber, in which case the exhaust is very thick, white and smelled of antifreeze.
Blowing air into the coolant, in which case the coolant tank would periodically over-fill and there were air bubbles in the coolant.
For bad rings, I'd expect to see dark, oily smoke and increased oil consumption.

 

[banjodunn]

G'day prob a bad valve so whip the head off it pistons will not come out the bottom, full engine rebuild kits are avail for about $500 so go for the full kit and get the head done and you should have it done in a day.
Good luck


Jon

 

[MikeyMonster]

Thanks for those replies.
I brought her back to the house, she started up fine out in the field and ran on the level fine but when i tried to go up a hill i got a backfire followed by a bigger one which kind of could of given someone shell shock. It stopped the engine and sent fumes through the oil breather and out the air filter container. Also on restart (which took a while) I noticed some fumes were constantly pouring out the rocket gasket. I guess thats from the gasket being worn there but whether there should be exhaust coming out of their normally i just dont know.

Heres a video of her running. Please excuse the small lawnmower tank that i used to get me home. I couldnt get the backfire to repeat, perhaps for some reason it requires a big load to do that. I rechecked compression and it was still 90 50 90 90.

 

[MikeyMonster]

Ive removed the rocker cover, there was two little bits of oily milky substance on the inside cover, im thinking that could just be from condensation over the years. Theres no other signs of water ingress and no sign of fluid loss from the radiator although i cant get an accurate reading on that.
Ive checked the rusted bolts on the out side of the head and on the exhaust manifold and they arent seized so i dont expect trouble there.

The rocker area is quite dirty, im tempted to run some diesel though the oil for a few minutes to clean her up a bit.
Looks like i will at least need to raise the head and check out the valves on that cylinder and then consider lifting up piston 2 for inspection.
Before i can lift the head I can see a few head bolts under the rocker cam that will need to be undone and also the connections from the push rods that will need disconnecting. Ive never dealt with valves before, they look like they must be under decent tension so are thus dangerous and need appropriate care.
I dont have a spring compressor and i live rural so visiting a parts place isnt very easy. Can i undo the push rods connection to the rocker arms by moving the engine to where the spring is extended to its max (not compressed to its max) and its seating the valve back in its seat and undoing the pushrod from the rocker arms then? Doing that to all rockerarms and then undoing the bolts which hold down the cam? Do i need to take note of adjustments then?

The worn rocket cover gasket can be seen as well in the photo

 

[MikeyMonster]

Ok i am pretty confident ive just shown that ive never rebuilt a four stroke before. To remove the rocket shaft it appears that all i need to do is remove the three or so bolts holding it down? As the rocker arms are actually not attached to the push rods and the rocker arms are also not attached on their other end to the top of the valve by the spring as the gap between the valve stem and rocker arm is what is measured as the valve gap.
So i hope to get this off during the weekend and report back on whether i can see the probable cause for the low compression.
Any further tips that could help would be appreciated.
It doesnt seem like getting this apart will be a hard task, so far

 

[Baby Grand]

Worn valve guide might be another low compression reason?
You'll know more when you get the head off.
Make sure you have the correct torque & sequence to put it back together before you take it off.

 

[Agvg]

You lift it right up, there are workshop manuals for download on the net, get one of those

 

[MikeyMonster]

Worn valve guide might be another low compression reason?
.

Im hoping its something to do with the valves, i really dont want to have to deal with a dirty oil pan etc if it is the rings. I hadnt known a valve guide could wear so thanks for pointing that out. A parts dept guy did actually give me a price on one of those guides and i had wondered why. Prices for things are relatively cheap, top gasket set $48NZ
($30US) and a valve is only $14. I plan to lift her up monday or tuesday depending on the weather.

 

[MikeyMonster]

You lift it right up, there are workshop manuals for download on the net, get one of those

Any chance of posting a link please. I have found that the head bolts are 100Nm and the rocker shaft is 60Nm. I was thinking that the head gasket tightening sequence would be inner to outer done in two stages.
I havent removed the pushrods but i assume i just pull them out before i lift the head.
My current job is detaching the thermost area from the front top of the head, after that il be lifting her.

 

[Agvg]

You have a PM

 

[MikeyMonster]

I found this link which is good
http://www.gralleklubben.se/wp-content/uploads/2013/10/GrålleManual.pdf
Interestingly they make mention on the rebuild section of the diesel engine that the pistons cant be removed with the engine in place as the piston head wont fit past the "crankshaft web" and the big end wont fit up the sleeve and out the top so to remove them you must lower the whole crankshaft out. They dont mention this point for the petrol version so im hoping that just isnt an omission by them, in case i do need to remove No2 Piston

 

[MikeyMonster]

You have a PM

Thanks for that, ive just seen it, im still learning my way around this site

 

[Jerry/MT]

Worn valve guide might be another low compression reason?
You'll know more when you get the head off.
Make sure you have the correct torque & sequence to put it back together before you take it off.

To the OP: It's a Harry Ferguson tractor not a Massey Ferguson and it should have a Standard Motors engine as it is a TEA model.

Worn valve guides will cause smoking at high manifold vacuum (idle and low rpm) but do not have any effect of compression pressure. The OP's problem appears to be a burned or misadjusted valve.

A blown head gasket would most likely have two adjacent cylinders with low pressure.

 

[Agvg]

Quite sure the piston goes up troug cylinder, had many TEA but its many years ago.

Nice tractor and cheap parts so a rebuild is an option.

 

[MikeyMonster]

Harry Ferguson, right got it (i think), thats before they merged with Massey. Thanks i wont forget that from now on.
I couldnt resist and ive taken the head off. A couple of tips for anyone doing this in the future including myself. Remove the bonnet and undo the fan belt and water pump and govenor clip, its all very easy just a few bolts. The push-rods can come out before or after lifting the head. Ive just left mine in. It looks as though they work by sitting in a cup that rides up and down from the crankshaft.
I lifted the head off by myself, heavy but not excessively- approximately 40kg i would guess.
Seems like you folks suspected diagnosis could be right. The headgasket looks fine, no cracking in the liners, the bores look fine with no scratches and all the piston domes have hard carbon on them, not excessive and not that soft stuff which indicates issues.

There is a tiny graze on top of the number one piston, maybe something went through the air intake, i cant even feel it with my fingers and its only piston number 2 with low compression and that looks fine. Im suspecting it will be something to do with the cylinder two valves now as well. Ive filled the cylinders up with diesel so i can give them a polish and all of them are holding the diesel levels constant so if piston 2 had bad rings i would expect that cylinders level to drop.

The engine is very dirty so im going to do my best to clean that all up, gunk in lots of places.
The way to tell which cylinder is what in those photos of the block is to look at the alternator which is near the front.
The head is now on the table at home and when i get back early next week i will update on what i find. Any tips about how to inspect a cylinder head, valves would be appreciated as this is my first one (as ive clearly displayed!)

 

[MikeyMonster]

Quite sure the piston goes up troug cylinder, had many TEA but its many years ago.

Nice tractor and cheap parts so a rebuild is an option.

Thanks yes im thinking they probably do come up too as its only the diesel they wrote up that issue about and they were quite pointedly about it.
Heres the pushrod chamber where they sit in the cups(which are removable) for anyone who hasnt seem them, heaps of gunk around this area.

 

[Quebecguy]

A simple way to check valve seating, now that you have the head off, is to turn it upside down (with the spark plugs in place) and fill the combustion chambers with gasoline. If you get anything more than a seepage (i.e. a dribble) past any valve you know you have a problem.

 

[banjodunn]

G'day Mikey first a note of caution DO NOT turn the engine over without something holding the liners down I normally have a large washer with a short bolt down into the head bolt hole I say this because it is easy for the liners to lift up and destroy the gaskets on the bottom of the liner and you will get water leaking into the sump, secondly as quebecguy said use some petrol and I pour it carefully in the intake and exh port with the head sitting on it's side and look for leakage past the valves. Seeing you have the head off any way I would give it a valve grind and check for straightness. Good luck with it and plenty of help here don't be afraid to ask a question.

Jon

 

[Agvg]

Any wear in the cylinder? If its wery worn then a engine kit might be the solution, how is the oil pressure?