qa125 blowby problem help

[izzy g]

not sure if the rings or pistons r bad i'm doing a compression test on it tomorrow and i will know what it is hopefully but here it is the engine sounds fine but once it's warm the oil starts to leak from the oil dipstick just a bit at idle there is a breather hose that goes from the carb to this black box im just wondering is it pluged or is there anything else i can do before i know i have a bad piston ring? the oil is new so it was not milky cause i didn't want to run it for long but when i pluged it with my hand the pressure went to the oil cap and when i took my hand off the fumes came froom the dipstick so now u know the bad now i just hope there is a better solution..thanks guys any suggestions or tips will help a lot .

 

[Philster]

Re: qa125 blowby problem help

Something is worn. Bad ring(s) or hole in piston.

Check the exhaust. Might have water intrusion that contributed, but might just be a very tired engine.

 

[izzy g]

Re: qa125 blowby problem help

the engine sat for about 3 years before i bought it so im not sure if that was also the case the weather might have something to do with it. would it be the head gasket too?

 

[Adirondack]

Re: qa125 blowby problem help

Excessive blow by is either indicative of a very tired motor, or a hole in a piston. To repair it a head gasket problem is pretty much irrelevent since your going to be there anyway. It already requires a rebuild or replacement.

If your looking to check low compression due to a hole in a piston as opposed to bad rings there is a not so scientific, or exacting test that's easy to perform. It's called a wet test. You check your compression as you normaly would, and note the compression. Then add a couple tablespoons of oil to the low cylinder. If there's marked improvement in the compression it's probably rings. If no improvement at all, most likely a hole in a piston. This also makes the assumtion that there are no bad valves on that cylinder.

Like I said. Not an exact science, but it can be an indicator.

 

[Aloysius]

Re: qa125 blowby problem help

rings can stick in their grooves (ring lands) in the pistons. A head gasket has no affect on blowby. Oil consumption is unrelated to compression.

Most pistons have 3 rings. The top ring is the main compression ring. The second ring is an oil scraper and back-up compression ring. The oil ring is a multi-piece ring that returns oil to the crankcase but contributes no compression function.

Ring seal against the ring lands is just as important as ring seal against the cylinder walls. You've got a serious ring sealing problem, probably due to lack of use.

 

[izzy g]

Re: qa125 blowby problem help

ok so we did a compression test on the motor and got 100psi on cylinder one no good 160 on cylinder 2 and 175 on 3 and 4. and then i put a little bit of oil in cylinder 1 waited about 5mins and cranked it again we got 200psi so no hole in the piston just a seal problem it seams, then we took the whole top end apart and found no hole in the pistons they look good just a little but of carbon on them. the walls look good no wear or scratches on them.i am almost positive that the piston rings in cylinder one are gone, can i replace it by droping the oil pan and undoing it from the bottom and torquing it with a light and a mirror from under? im not a pro so good advice is much needed thnks.izzy

 

[izzy g]

Re: qa125 blowby problem help

should i put a new crank rod bearing when i replacce it r not? i hope i don't have to take the motor out there is a lot of room from the bottom.

 

[Adirondack]

Re: qa125 blowby problem help

None of the above. I wouldn't recommend anything close to what your talking about. These engines aren't CAT diesels. Either remove the engine and do a proper rebuild, or leave it alone and wipe up the oil with a rag every once in a while. What your proposing is wrong on more levels than I can mention here, and will simply cause more problems than your fixing.

 

[Aloysius]

Re: qa125 blowby problem help

You may end up buying pistons. It's doubtful the rings are "gone", but are stuck in their lands. As such, ring land condition is extremely important. Worn or damaged lands will cause leakage even with new rings. If you're not experienced in working with pistons, you can do more harm than good.

I agree that it's unlikely you can cheat this one. do it right...pull the motor. time for seals and gaskets anyway.

 

[Adirondack]

Re: qa125 blowby problem help

Without seeing it I would still be surprised if there is enough room below the engine to get the pan off past the oil pump pickup anyway.

 

[izzy g]

Re: qa125 blowby problem help

so if i replace the head gasket and timing belt,put it back together and just use it till the end of fall it should be ok? i don't mind doing that and just do a full rebuild during the winter. is it safe to use it like that? i'm not the kind of guy that abuses stuff i just want to get from point a to b when i go to the lake. the motor sound great even the way it was before that's why i was so shocked about the rings.fml.

 

[Adirondack]

Re: qa125 blowby problem help

so if i replace the head gasket and timing belt,put it back together and just use it till the end of fall it should be ok? i don't mind doing that and just do a full rebuild during the winter. is it safe to use it like that? i'm not the kind of guy that abuses stuff i just want to get from point a to b when i go to the lake. the motor sound great even the way it was before that's why i was so shocked about the rings.fml.

There's never a guarantee, but as long as there is nothing coming apart in the bottom end, and no knocking, that would have been my plan before pulling the head. Do a proper job putting the head back on and it probably will. Only thing you have to lose is a head gasket set.

 

[izzy g]

Re: qa125 blowby problem help

that's true. thanks this is crazy cause i ran it a bunch of times in my driveway in a container and it ran awsome no nocking or anything exept for the oil leaking from the dipstick tube.i was looking at a few similar threads and somebody mentioned the mmo oil trick and how they he saved people a few motors can the seal problem correct itself with use eventually?. i will have her back together next week and i;ll post the results but feel free to throw a few more tips they are very usefull i really appreciate it....

 

[Adirondack]

Re: qa125 blowby problem help

Things rarely fix themselves, but if you put it into perspective, you have 100 pounds compression in the one bad cylinder. It's a 4 cylinder with about 150 pounds in the rest. That one weak cylinder is costing you less than 10% of your power. You looked in the cylinders and saw no visible damage so as long as the head goes back on right no additional damage should occur. Like you said it ran good. Keep a rag on board and do a little house cleaning from time to time for the rest of the season. Then you can feel good about starting out with a nice fresh motor next year.

Just a thought. While it's sitting there waiting to be put back together and re-started let that cylinder soak in a little automatic trans fluid or marvel mystery oil. It can't hurt, and who knows?

Happy boating.

 

[izzy g]

Re: qa125 blowby problem help

sweet thanks i'll go do that and i'll post as soon as i get some results thanks again for taking your time to explain things to me..cheers.

 

[Philster]

Re: qa125 blowby problem help

If you did an HP check, I'd bet it'd be off by less than 10%. Run it and use it and see if she works for you. Heck, mine is worse off and the darn thing is off it's factory top speed by about 1-2 MPH. Oily mess from blow by tube, and every test says she should be a dog, but she idles, accels and pulls fine. My oil pressure is fine. I know an engine builder who dyno engines with much much worse issues, and he is always surprised by how little HP they lose. If drivability is there, then use it. In a drag car, 3% loss of HP matters.... in a boat... you won't notice. Some folks will mention adding SOME thicker oil... and I agree. Thicken the oil up by adding some straight-weight thicker oil...

MMO and/or trans fluid are good lubes that are harmless. Don't restore any compression, but they can actually do a little more cleaning around rings and stuff.

 

[izzy g]

Re: qa125 blowby problem help

sounds good i think thicker oil will help and i'll try the other options too as long as i can use it i don"t mind taking it out in the middle of winter.i'm just glad i can still use it