Diesel (tractor) compression?
Discussion
Father bought recently a 1960's International Harvester B275 Diesel tractor (whilst our good on is undergoing an engine rebuild), just to pootle about on to move big bales etc, on the proviso that the head gasket needed replacing.
The head gasket was evidently gone when we removed the head to replace it.
The engine had also evidently had some work done to it in its 40 years, the number three piston and valves were new, as was the liner.
All the head bolt threads had also been helicoiled (and then we got a tap snapped in one, but that is a different story)
anyway, number 4 piston had a bit of play in the liner, but given that its a 40 year old tractor, we put it all back together again on the basis that if it only ran on three cylinders for a couple of months it would have done its job.
The engine will only fire on the 3rd cylinder, have tried putting the same injector onto the first cylinder, and its still the third cylinder that fires.
Borrowed a compression tester and pistons 1,2 and 4 are producing 150psi, whilst piston 3 is producing 200psi.
Does anyone here know if 150psi is enough pressure to fire with, and therefore something else must be amiss or are we going to have to do the rings? I really don't want to have the head off again on account of the helicoils.
Haven't had much/any experience with diesels.
Bit embarrassing really, possibly the worlds most basic engine and we can't get the bastard thing to run!
Cheers,
Chris
>>> Edited by chris1roll on Friday 14th January 21:47
The head gasket was evidently gone when we removed the head to replace it.
The engine had also evidently had some work done to it in its 40 years, the number three piston and valves were new, as was the liner.
All the head bolt threads had also been helicoiled (and then we got a tap snapped in one, but that is a different story)
anyway, number 4 piston had a bit of play in the liner, but given that its a 40 year old tractor, we put it all back together again on the basis that if it only ran on three cylinders for a couple of months it would have done its job.
The engine will only fire on the 3rd cylinder, have tried putting the same injector onto the first cylinder, and its still the third cylinder that fires.
Borrowed a compression tester and pistons 1,2 and 4 are producing 150psi, whilst piston 3 is producing 200psi.
Does anyone here know if 150psi is enough pressure to fire with, and therefore something else must be amiss or are we going to have to do the rings? I really don't want to have the head off again on account of the helicoils.
Haven't had much/any experience with diesels.
Bit embarrassing really, possibly the worlds most basic engine and we can't get the bastard thing to run!
Cheers,
Chris
>>> Edited by chris1roll on Friday 14th January 21:47
Compression is the key to getting a diesel running,
I assume you've checked and adjusted the valve clearences, after all, if the air can't get in you can't compress it, and it's the compression that produces enough heat build up for the diesel to ignite.
Have you tried giving it a little sniff of eazistart ?
that will more often than not give the engine a higher chance of catching during the cranking stage. once it's running the increased piston speed will help to build up sufficient heat in the air to allow combustion.
I assume you've checked and adjusted the valve clearences, after all, if the air can't get in you can't compress it, and it's the compression that produces enough heat build up for the diesel to ignite.
Have you tried giving it a little sniff of eazistart ?
that will more often than not give the engine a higher chance of catching during the cranking stage. once it's running the increased piston speed will help to build up sufficient heat in the air to allow combustion.
Hi, thanks for the reply,
I take it you think 150 is enough compression? Everyone we have spoken to seems to think it is, just seems a little suspicious that it will fire on the one with 200...
Its a pushrod engine, and the clearances are adjusted by a bolt on the rocker, it seems they just need to be adjusted so they are contacting the top of the valve stem when the valves are closed, which they are.
We have tried easy start, it usually just makes a massive clunk and stops the engine from turning over, which we're assuming is because it is igniting far far too early, when the piston is still on the compression stroke. Then i got a face full of it because i was standing across from the air inlet and my mate missed
(made my mouth dry :sick: )
Had another go at it today, and we think we had a good five seconds of firing before it died again, this seems to be too long for it to be just running on easy start?
It seems that we need to get it turning over faster, tried towing it with ye olde volvo but it almost stalled the car when i dropped the clutch. probably have another go in daylight tomorrow.
The only other thing we can think of is that the pump isn't producing enough pressure, or the timing on it is out so its not opening the injectors at the right time, but i would think if there was enough diesel in there it should ignite on the next stroke?
the timing is all done by gears, there is no belt or chain, so it can't have slipped, but the pump is blatantly not the original one, so it might have been set up wrong.
Sorry for all the "thinking aloud" but i think if i give as much info as possible it is usually more usfull
Chris.
I take it you think 150 is enough compression? Everyone we have spoken to seems to think it is, just seems a little suspicious that it will fire on the one with 200...
Its a pushrod engine, and the clearances are adjusted by a bolt on the rocker, it seems they just need to be adjusted so they are contacting the top of the valve stem when the valves are closed, which they are.
We have tried easy start, it usually just makes a massive clunk and stops the engine from turning over, which we're assuming is because it is igniting far far too early, when the piston is still on the compression stroke. Then i got a face full of it because i was standing across from the air inlet and my mate missed
(made my mouth dry :sick: ) Had another go at it today, and we think we had a good five seconds of firing before it died again, this seems to be too long for it to be just running on easy start?
It seems that we need to get it turning over faster, tried towing it with ye olde volvo but it almost stalled the car when i dropped the clutch. probably have another go in daylight tomorrow.
The only other thing we can think of is that the pump isn't producing enough pressure, or the timing on it is out so its not opening the injectors at the right time, but i would think if there was enough diesel in there it should ignite on the next stroke?
the timing is all done by gears, there is no belt or chain, so it can't have slipped, but the pump is blatantly not the original one, so it might have been set up wrong.
Sorry for all the "thinking aloud" but i think if i give as much info as possible it is usually more usfull
Chris.
I couldn't help the chuckle when I read you'd tried to tow a tractor with a volvo 
I'm surprised it didn't rip the back of the car off.
You said you'd swapped the injectors over and still only Number 3 manged to fire, so you can rule out critically poor atomisation of the fuel.
Old tractors usually had an inline fuel pump, so the point of injection can be easily checked by spill timing.
and a fuel quantity error will affect all cylinders as the delivery amount is govened by a common rack.
Going back to fact that it only picks up on No3 it seems obvious to me that the lower compression is the cause, Eazistart will cause the engine to lock up if it's sprayed in in too large a quantiy.
When it did fire and run for a small time, did you get it revving above idle?
i'd have been tempted to floor the throttle and really get those pistons moving.
Are you sure it didn't stall because of air in the fuel system after the heads been off?
I'm surprised it didn't rip the back of the car off.
You said you'd swapped the injectors over and still only Number 3 manged to fire, so you can rule out critically poor atomisation of the fuel.
Old tractors usually had an inline fuel pump, so the point of injection can be easily checked by spill timing.
and a fuel quantity error will affect all cylinders as the delivery amount is govened by a common rack. Going back to fact that it only picks up on No3 it seems obvious to me that the lower compression is the cause, Eazistart will cause the engine to lock up if it's sprayed in in too large a quantiy.
When it did fire and run for a small time, did you get it revving above idle?
i'd have been tempted to floor the throttle and really get those pistons moving.
Are you sure it didn't stall because of air in the fuel system after the heads been off?
Hi all, thanks for the replys 
Found out how to adjust the pump timing, it was a little out, but not a lot. Its a rotary CAV pump BTW.
Further investigation has suggested that the compression for this 46hp engine should be 250-300psi, so that probably explains the following:
Well, its defintely knackered!!
If you laughed at towing it, you'll probably laugh at this then....
Finally got it to run, using,
A) tractor battery on the tractor
B) Tractor battery on the floor connected Via jump leads,
c) the 740, running at about 4000 rpm, connected via another set of jump leads
D) Half a can (not kidding) of easi start.
all at the same time.
It made the loudest mechanical knocking noises you could imagine, and there was more smoke coming from the oil filler/breather than there was from the exhaust, due to the incredible amount of blow by, and then it was spurting oil out of it, so we put another exhaust pipe on it (as my 12yr old brother put it, "twice the pollution, half the go")
and ran it untill hot, then the seal on the oil filter let go, and it depsited a good half gallon of oil on the floor and we had to stop it.
we were hoping getting it hot may have released any stuck rings, but guess what, no way would it start again, even after a pause and run to get a further two cans of easy start.
Think its fairly safe to assume the rings are shot to pieces, and the big end bearings sound as if they have about 2mm play in them, so it certainly wasn't 2just the head gasket"
So, we now have two rebuilds to do.
My father hasn't been to pay the guy yet, and he is supposedly an agricultural engineer, so he's going to have some very stiff words with him this week.
Incidentally, about towing it with the car, we have done it before with our good tractor, and it works, car doesn't like it much though.
The only reason we are rebuilding the ours is because the liner seals had perished, and as we had to have the engine almost completelt stripped, thought we may as well do it properly, as the tinwork and everything on it is pretty good. Ought to have just got on and done that in the first place. C'est la vie!
>> Edited by chris1roll on Monday 17th January 19:34
>> Edited by chris1roll on Monday 17th January 19:35
Found out how to adjust the pump timing, it was a little out, but not a lot. Its a rotary CAV pump BTW.
Further investigation has suggested that the compression for this 46hp engine should be 250-300psi, so that probably explains the following:
Well, its defintely knackered!!
If you laughed at towing it, you'll probably laugh at this then....
Finally got it to run, using,
A) tractor battery on the tractor
B) Tractor battery on the floor connected Via jump leads,
c) the 740, running at about 4000 rpm, connected via another set of jump leads
D) Half a can (not kidding) of easi start.
all at the same time.
It made the loudest mechanical knocking noises you could imagine, and there was more smoke coming from the oil filler/breather than there was from the exhaust, due to the incredible amount of blow by, and then it was spurting oil out of it, so we put another exhaust pipe on it (as my 12yr old brother put it, "twice the pollution, half the go")
and ran it untill hot, then the seal on the oil filter let go, and it depsited a good half gallon of oil on the floor
and we had to stop it. we were hoping getting it hot may have released any stuck rings, but guess what, no way would it start again, even after a pause and run to get a further two cans of easy start.
Think its fairly safe to assume the rings are shot to pieces, and the big end bearings sound as if they have about 2mm play in them, so it certainly wasn't 2just the head gasket"
So, we now have two rebuilds to do.
My father hasn't been to pay the guy yet, and he is supposedly an agricultural engineer, so he's going to have some very stiff words with him this week.
Incidentally, about towing it with the car, we have done it before with our good tractor, and it works, car doesn't like it much though.
The only reason we are rebuilding the ours is because the liner seals had perished, and as we had to have the engine almost completelt stripped, thought we may as well do it properly, as the tinwork and everything on it is pretty good. Ought to have just got on and done that in the first place. C'est la vie!
>> Edited by chris1roll on Monday 17th January 19:34
>> Edited by chris1roll on Monday 17th January 19:35
the leakage test would have shown that the rings/bores were humped but i only saw the topic this evening, sorrychris1roll said:
Hi all, thanks for the replys
If you laughed at towing it, you'll probably laugh at this then....
Finally got it to run, using,
A) tractor battery on the tractor
B) Tractor battery on the floor connected Via jump leads,
c) the 740, running at about 4000 rpm, connected via another set of jump leads
D) Half a can (not kidding) of easi start.
all at the same time.
It made the loudest mechanical knocking noises you could imagine, and there was more smoke coming from the oil filler/breather than there was from the exhaust, due to the incredible amount of blow by, and then it was spurting oil out of it, so we put another exhaust pipe on it (as my 12yr old brother put it, "twice the pollution, half the go")
and ran it untill hot, then the seal on the oil filter let go, and it depsited a good half gallon of oil on the floor
I was living this with you mate. Thanks for sharing it.
I could just picture a few seconds of subsequent deafening silence and then through the clearing smoke , an oil stained urchin like face appears and a squeaky 12 year old voice says very sagely " Oh dear, Dad's gonna be mad now ,looks like we've f
ked it"Well, just to update on proceedings, we went ahead and bought all the parts needed to fix our "proper" tractor.
It now has 4 new cylinder liners,
4 new liner seals (this being the original problem!)
New set of piston rings,
New set of big end bearings,
Skimmed head and lapped valves.
Once we had fitted the new liners and rings you could tell instanly there was going to be a load more compression as the engine was much harder to turn over, even with the head still off.
After fitting the head we turned the engine over with no glow plugs/injectors in it to get oil all round before starting it, the after and bleeding the fuel pump, we pushed it outside (learnt that one!) and started turning it over with the unions off the injectors to bleed them. as soon as the first union was close it started firing, and once all four were done it sounded (for a tractor!) very nice.
Let it warm up, then took the rocker cover off again to retorque the head bolts. Almost turned into a complete F disaster at that point. torqing up the last head bolt and SNAP!! 
At that point we started whimpering and wanted to withdraw into a foetal position in the corner.
removing the portion protruding showed that it had snapped in such a way it formed a "key" and reinserting it and unscrewing whilst applying downwards pressure actually unscrewed the snapped portion from the head. of course this still left the end of a bolt approximately 4 inches down in the hole. After half an hour vainly trying to hookit out with a pair of tweezers I was going through the drawers looking for something more usefull and came across a tube of superglue.
Drop on the end of the bolt, hold it in tight for 30 seconds and...out it came! 
Replaced the bolt, gingerly torqued it all up, replace rocker etc, literally touched the starter and she fired up straight away.
Forgot to take the compression tester but might do it sometime just out of interest.
>> Edited by chris1roll on Thursday 3rd February 21:04
It now has 4 new cylinder liners,
4 new liner seals (this being the original problem!)
New set of piston rings,
New set of big end bearings,
Skimmed head and lapped valves.
Once we had fitted the new liners and rings you could tell instanly there was going to be a load more compression as the engine was much harder to turn over, even with the head still off.
After fitting the head we turned the engine over with no glow plugs/injectors in it to get oil all round before starting it, the after and bleeding the fuel pump, we pushed it outside (learnt that one!) and started turning it over with the unions off the injectors to bleed them. as soon as the first union was close it started firing, and once all four were done it sounded (for a tractor!) very nice.
Let it warm up, then took the rocker cover off again to retorque the head bolts. Almost turned into a complete F
disaster at that point. torqing up the last head bolt and SNAP!! At that point we started whimpering and wanted to withdraw into a foetal position in the corner. removing the portion protruding showed that it had snapped in such a way it formed a "key" and reinserting it and unscrewing whilst applying downwards pressure actually unscrewed the snapped portion from the head. of course this still left the end of a bolt approximately 4 inches down in the hole. After half an hour vainly trying to hookit out with a pair of tweezers I was going through the drawers looking for something more usefull and came across a tube of superglue.
Drop on the end of the bolt, hold it in tight for 30 seconds and...out it came! Replaced the bolt, gingerly torqued it all up, replace rocker etc, literally touched the starter and she fired up straight away.
Forgot to take the compression tester but might do it sometime just out of interest.
>> Edited by chris1roll on Thursday 3rd February 21:04
Thanks... theres some pics of the liners going in using the jig we fabricated if anyones interested...
http://photobucket.com/albums/v477/chris1roll/Tractor/
Would have taken some of the pistons etc but the camera battery ran out, we made a ring compressor too.
EDIT: no comments on the blobby welding, the welder needs a new torch and hose!
>> Edited by chris1roll on Saturday 5th February 20:23
http://photobucket.com/albums/v477/chris1roll/Tractor/
Would have taken some of the pistons etc but the camera battery ran out, we made a ring compressor too.
EDIT: no comments on the blobby welding, the welder needs a new torch and hose!
>> Edited by chris1roll on Saturday 5th February 20:23
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