I know the obvious re: blow-by but I still need some advice please. The engine is getting oil in the air cleaner, I'm running 10W-30. Would 10W-40 or 20W-40 help a bit? Rislone, Restore, SeaFoam, ??? I would think that if the rings are worn a proper job is a re-bore, etc. But would pulling the pistons from below and installing new rings work or is it just wishful thinking? The truck is a carb fitted '87 F250 and I'm asking you guys because the '87-.. crowd is mainly FI'ed. thanks.

 

For oil in the air cleaner, check the PCV for proper operation, check the breather etc.

I take it the oil is coming up the breather side, which should be pulling air into the engine, not puking oil out.

Have you ever pulled the valve covers? MAYBE your valve covers have enough gunk built up to cause the PCV to malfunction.

Thicker oil? Probably not going to help.

Pistons won't come out the bottom, at least not in one piece!

JMO, but I would go shopping for a 351w block and build a new motor as this one fades out. ymmv.

 

Thanks, I'll check under the valve covers. The PVC valve (on the right side of engine) rattles so I presume it's OK. The breather side is just a cap that seals where you pour in oil so I don't know if there is an actual breather. I have pulled pistons out the bottom but that was on a vintage flathead Chrysler engine. I may look at getting another engine but I only use the truck occasionaly to go to the dump, lumber yard, etc.

One other weird thing... the "fuel storage canister valve" melted somehow near the bottom. No fire or anything but the engine did overheat awhile back. Any ideas re: that????

 

Disconnected the hose that goes from the oil filler tube to air cleaner. (I presume that this brings in clean air into the engine as the PVC side sends in dirty air.) Anyway, I expected to see a lot of oil on my manifold as that is where I laid the hose. No oil! So, if oil was being forced into the air cleaner at this point how come no oil is coming out now?

 

The engine has to warm up, and usually the blow-by is worse under load. Re-ringing the pistons will work for about 6 months to a year, and then it will be back. The problem is the bores wear out-of round, and the pistons wear also. So the pistons are slapping around in a out-of-round bore, so it's hard for the rings to do their job.

What I have done is take the hose off the air-cleaner, and put a longer hose on it and run it down along the frame and let it puke out on the ground. The general consensus from the motorcycle crowd is please use a can to catch most of it so it doesn't get on the roadway. I don't have a vehicle with this apparatus on it now, but it would be simple enough to put a catch can on it if I did. You can run most engines a long time like this, so long as they don't start fouling the plugs out.

 

Yeah, I knew that the "ringing" would be a temp fix. And I thought about attaching an rad overflow container and catching the oil that way. But what I really want to know is why there is no oil coming from the hose i disconnected. The engine was up to operating temp for about 45 minuntes and I was put under load a few times going up hills and "booting it". So who can explain this to me? The little mesh filter inside the air cleaner was removed as well. Maybe that was the cause? Would a new clean one solve the problem? I'm stumped.

 

There are other signs that go along with lots of blow-by and a wore out engine.
1. Knocking and or rattling noises, especially on start-up
2. Uses a little bit or a lot of oil
3. Has a lot of miles on it

These usually go along with a lot of blow-by indicating the engine has a lot of wear. If you have none of these other symptoms, but suddenly had a mysterious episode of high blow-by, it could be one of the rings was temporarily stuck. This usually happens on a engine that is in good shape, but has sat around a lot. If this is the case, and the ring has become unstuck, you may never see the problem again as long as you drive it occasionally.

 

I guess I'm confused, I'm not seeing why you would be expecting to see oil coming from the non-PCV hose.

There is a hose connecting the engine & air cleaner, and there is a filter in the air cleaner for that hose. That hose supplies fresh air into the valve cover to replace the air that gets sucked out via the PCV valve.

 

When the hose is connected, the vacuum in the airfilter housing is overcoming the vacuum in the engine which is regulated by the PCV.

It is also possible the oil returns are somewhat plugged, and oil builds to above normal levels in the valve covers. This, I would think, would cause the PCV to stop the flow, and would allow the oil to more easily go up the hose to the filter housing.

I would pull the valve covers just for giggles and see how the drains look, how much gunk is in there, etc.

 

There was oil in the air filter. Therefore I expected the oil was being pumped up out of the valve area but none has shown up in the area I laid the hose after taking it off the air filter but leaving it attached to the valve cover.

I'm hoping it was a stuck ring but I'm going to re-attach the hose to the filter in a couple of days to see if the problem returns. Maybe it was being sucked into the filter rather than being pumped. I may then pull the covers off and check the condition around the rockers, valve stems, etc.

The truck is an '87 with 180,683 KMs or approx. 110,000 miles which I don't consider high. Was used mainly to haul a camper before I got it.

 

Found this link courtesy of another member here:

Positive Crankcase Ventilation (PCV)

You might get lucky with your plan.

 

Thanks so much for this info. I'm going to check the truck again today. According to that article the crankcase gasses are sucked into the carb. If the hose is not attached then the gasses would have a harder time escaping causing a pressure build up in the engine. Therefore if the presure is too high it could be forcing oil into the air cleaner rather then the air cleaner forcing air into the engine. Sound correct? I'll pull off everthing later to check; perhaps the PVC hose is not connected. Thanks again.

 

Yes, you are on to it. Other things to check would be clogging/plugged hoses, carb or manifold inlet, and of course, the possibility of sludged up valve covers including the baffle under the PCV.

 

Thank you again!!! Went ahead and really checked out the system. But it was quite obvious after all. Some one recommended a fellow last year who could get the truck through emissions check by disabling the extra emissions plumbing and it did pass. But the dumb bugger dis-connected the hose from the PCV to the carb (had another non-fuctioning hose hooked up instead)!!! I don't drive the truck that much and didn't notice anything until last week when I checked the air cleaner and found an oil soaked filter and pools of oil in the housing. Consequently the high pressure inside the engine caused the oil to be forced into the air cleaner. NO actual blow-by in the typical sense. Hooked everything up correctly, test under load for about 20 minutes and no oil! Engine seems to breathe easier and has more pep. Thanks for all the imput and comments. No need for a replacement engine.