MF 40b Perkins AD4.203 blowing oil

gjinc

Member
HI
A few years ago, 57 hours on the meter I replaced pistons, rings, sleeves on my engine because it was blowing oil out of the crank case breather. I found several rings broke. 7 hours ago on the meter I re-torqued the head. Last night the motor started blowing oil out of the breather tube again. I'll be tearing into the motor sometime in the near future but I thought these perkins were suppose to last longer than 57 hours.
Any ideas???
 
When you installed the pistons,did you check the ring end gaps and make sure the ring
gaps were staggered before installing? You used plenty of oil on the pistons, and
lightly lubes the cyl walls? Were the cyl walls honed?

Can you lay hands on a compression tester?
 
HI,
Yes, rings were staggered, end gap checked. Cylinders were honed. I had a engine build oil i used when installing the pistons, can't remember what it was called. The MF dealer uses it, so i used it.

I can get a compression tester, but don't think it will tell me anymore or keep me from pulling the head.
Tell me what your thinking is.
thanks
 
HI,

Yes, rings were staggered, end gap checked. Cylinders were honed. I had a engine build oil i used when installing the pistons, can't remember what it was called. The MF dealer uses it, so i used it.

I can get a compression tester, but don't think it will tell me anymore or keep me from pulling the head.

Tell me what your thinking is.

thanks
 
Before you tear it down recheck your service manual for how to adjust the rocker arm shaft. If engine starts and runs well you may have too much oil at the top if shaft is turned wrong. Also check the air cleaner and all connections, if there's a hole in the piping to the engine dust that gets in will take out the rings again..
 
Hi, Yes it starts easily, runs smooth. I will look that up and check it out. I will also look at the air cleaner and piping.
Thanks
 
Hi,
Could it be that the engine has glazed up? Has it done heavy work since it was overhauled? Is it also "spitting" oil from the exhaust? These engines need a sufficent load on them initially to "bed in" the rings, along with a good run in or monograde oil. Just a thought, Evan.
 
Well, my thinking is the only way to pressurize the crankcase is with combustion blowby, so somehow exhaust gas is getting by the rings. Don't see how retorquing the head would cause that, unless by some incredible dint of bad luck you cracked the head gasket in some way that lets exhaust gas into the oil gallery that didn't affect the water jacket. Even if the engine starts and runs smooth, that doesn't mean compression isn't low on one or more cylinders.If you suspect cylinder wall glazing, depending on how low compression readings are, there is a trick you can think about called "Ring Job in a Can". Cat used to have it as an approved service method for glazed cylinders. I read it in the manual of my 977.

Get some Bon Ami, or Bartender's Friend.Both contain very fine abrasive. Bartender's Friend is better because it is a crystal that will dissolve. Remove your air cleaner. Start the motor and let it warm up. Increase the rpms to 800-1000 and hold no more two or three teaspoons of the stuff under the air intake so the engine vacuum draws it up into the intake slowly. The very fine abrasives will work to remove the cylinder glaze, and get blown out the exhaust. Then change your oil.

Not something you want to do every day, but I have seen it work, mostly to reduce oil consumption resulting from glazing problems. But if you've got enough blowby that you're seriously slobbering, like need a catch can, out the breather I'd suspect issues. I have also seen ring gaps align themselves for a while, then "fix" themselves, but pretty much only in air cooled Lycomings. But if there's no overheating or other symptoms, you might want to just work it like a rented mule for ten or twenty hours, keep a close eye on the oil level, and see what happens. 57 hours is not really enough time for the rings to seat properly, unless you've been really working it hard. If no joy, then try the Bon Ami trick.

Have you gone through your parts list to be certain you go the right piston/ring/cylinder numbers? I have a Perkins AD192 in my tractor, when I did my motor the shop sent me parts for a AD203 the first time around. Everything looked about exactly the same, but I mic'd it all and then had to send the kit back.
 
HI, I thank everyone for the replies. It has not been worked hard at all. I did not say this is a loader/ backhoe 40B, sorry for any confusion.
Looking back at my parts receipts I did the overhaul in 2011, correct parts, so 57 hours in 4 years. What I learned is it is not really broke in at all.
I see where the compression tester might show which cylinder or cylinders to focus on.
I lost about 1 gallon of oil in about 50 minutes of use, around 1800-1900 rpms driving down the road.
I did not know about the rocker arm shaft.
Last night I used it for about an hour at about 1400 rpms and I had no oil come out the vent tube. I was expecting it to blow out and had a bucket under the tube.
Today I drove it 10 miles back to the shop(about 1 hour), I did not go over 1400 rpm and had no oil out the vent.
I don't really seem to need to go over 1400 rpm
What I am thinking is I will do the compression test, and I will take a look to see where the rocker arm shaft is set at and adjust it. I think that is as far as I will go for now until oil starts coming out at 1400 rpms.
Is my thinking horribly wrong?
Thanks
 
I have a 3-cyl. 152 cid Perkins in my MF. I used to idle it along, gently, til I read in my manual not to do that. My manual says to warm it up at 1200 RPM for several mintues. then operate it at 1700 RPM. D0 NOT just idle along.
 
With that usage history, the other problem you could have from sitting, depending on
where you are and storage conditions, is that rust formed on the cylinder walls and
when you began running it scraped off and gotten into the ring lands seizing the
rings.The two choices there are flogging it all the way back to the barn and hoping
it clears itself out, or doing a "ring wash", which is essentially pulling an
injector and flooding a cylinder with Marvel Mystery Oil at the top of a compression
stroke, trying to force a little solvent through the rings and hoping that loosens
the crud.

Do the compression test, run it hard, test again and see if anything changes.
 

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