hdizzle

So, I posted a thread a while back in the fall about a truck I purchased with a "rebuilt" engine.

This engine was losing a lot of oil, and I thought most of it was burning off due to a lack of proper break-in. However, since purchase I've driven it about 2500-3000 miles and tired carrying a bedload of stuff up hills, gear braking, etc, and oil consumption improved somewhat (150 miles/quarter) then got worse again (back to ~100 miles/quart). Recently I noticed that a lot of the oil seems to be lost on startup, with a nice fine mist of oil coming out of the tailpipe.

I'm getting towards the end of my rope here, I bought the truck for $1400 and I've probably spent close to $2300 on fixing it up, It's up for sale right now for $1700, but most people who call don't understand what I'm talking about when I try to explain the engine problem, lots of no shows, etc. Pretty frustrating. I'm wondering now whether I should just try to find another engine to put in and hope it will be better, or to cut my losses and sell before something else big goes (transmission?)

So, 2 questions really, to sell or not to sell? and If I get the engine replaced, how much do I expect to spend? (Don't have the facilities or knowledge to do it myself).

abecedarian

Have you replaced the PCV valve? What do the spark plugs look like?

hdizzle

I haven't replaced the PCV valve, I will try to get pictures of the sparkplugs up.

hdizzle

Replaced PCV valve on Saturday, didn't get a chance to drive her around too much, but it does seem to idle smoother and I haven't gotten any oil spray on my hand when I hold it up to the exhaust, sometimes it seems worse after it's been sitting for a while so I'm letting it sit today and checking after work to see, if nothing else it seems to be smoking less when you get on the throttle and running a bit smoother. It would be awesome if this even let me get another 6 months to a year out of this truck.

abecedarian

What weight oil are you using? If the problem is worn rings, upping the oil to a 20w-50 or even straight 50W may help reduce the blowby problem. You could even add a pint of 80W gear oil... but that's getting extreme.

Don't tell anyone I told you this, but maybe, at your next oil change, replace your oil with 1/2 pint seafoam, one quart of dexron II transmission fluid and top the case up with 50W and run it til the next change. The seafoam and ATF may unstick the rings enough to get them to seal better. Keep an eye on your oil pressure / idiot light though.

hdizzle

I have been using 10w-40, but when I got the truck they had been using 5w-30 for the first 1000 miles or so on the rebuild. I am thinking about going up in weight again if necessary.

I though the PCV valve had it all fixed, but I drove to work today and she blew oil out the tailpipe out at idle both at home, and then 6 miles later when I got to work, which wasn't very encouraging. It seems like I tend to get more oil blowing out when it's colder (about 45 or 50 degrees out this morning).

I don't think it's that the rings are worn, they just aren't seated or else they should have been oversized and they weren't. Who the heck knows though, it seems like if it was that bad it would be smoking a ton, but it's not, I really though the PCV valve had it all taken care of, and it is running more smoothly and not smoking in any way that I can see.

Also, the air cleaner doesn't have any oil on it, just as a troubleshooting note

But all the oil out the tailpipe is pretty concerning, really concerning actually.

john rumbo

if it doesnt smoke when your driving it sounds like you could have a problem with your valve guides not sealing so when it sits it drains into the cylinders and at startup it burns your oil off quick easy fix sometimes will smoke alittle when idleing for long periods of time

hdizzle

Good to hear that it might be quick and easy. I don't really know anything about working with valves, what would I have to do to fix the problem?
Thanks for your help!

mmcpeck

You'd have to pull the head off, take the valves out and replace the guide seals, not that quick and easy. When they wear they don't seal right away on start up and oil shoots down them into the combustion chamber, then after a few sconds of running they heat up and expand and seal, but if they are bad enough, they will continue to leak.

It may have only been the block that was rebuilt and they didn't touch the head, so it may be worth it to get the head re-done on it.

john rumbo

you can pull valve cover off remove rocker arm assemble pressurerize cylinder with piston all the way down with air use compress air from air tank remove valve spring install a valve spring unbrella its a rubber cover that goes under the spring on the valve stem to reseal the stem and reinstall same as disassemble they sell the sparkplug to air adapter for this purpose hopefully this helped

hdizzle

Just to follow up on this (albeit very much later). I did a compression test and it is pretty uniform across all cylinders (135 to 140) that's cranking over 4 times before checking. I wasn't too concerned about absolute numbers, mostly uniformity. The one where I got a 135 I also don't think I got a good seal with the tester. When I pulled the plugs they looked like it had been running lean, and burning oil (white, powdery, caked on thick residue). Looked very much like the plugs on an old plymouth I used to have with bad valves.

I switched over to high mileage oil and consumption has dropped, though the truck seems to be smoking more, but spitting oil less. I'm still trying to figure out what exactly to do with the valves, I'm pretty intimidated by the job and I think I will end up having to take the head off to do it correctly. Truck is up for sale right now, but I have so much into it I doubt I will get my asking price. (haven't had a call about it so far).

Thanks to all who have helped!

84sr5yoty

135-140 PSI is too low for that mileage.

Have you adjusted the valves? Proper valve adjustment is critical for accurate compression #'s. Too tight or too lose clearances will cause very low (or even 0) PSI.

DudeBud

that works great on motors that don't use the head bolts to fasten the rocker arm assembly, you'll destroy the head gasket doing it this way on a R series motor.

hdizzle

I haven't ever adjusted the valves.

I'm not too confident on the absolute numbers for the compression test, I was using a pretty old tester and I'm not sure on the quality of the seal on each one - I was using a tester that had a seperate screw-in adapter to go from 5/8 to 13/16 and on the first cylinder I almost got it stuck to the point of needing to remove the exhaust shield and other pieces to get it out.

After that, I tried to make sure nothing was on there too tight, because I don't have any crows feet or other tools to get in there ver well. I was mostly trying to make sure that I was consistent with the number of seconds I cranked (about 4ish) across each cylinder and how well everything was connected. Mostly I was trying to make sure that there wasn't something wrong with a broken ring or something like that.

I was reading someone else's post on here a while back about how they were getting something like 140/170/210 on their compression depending on how long they let the engine crank. I guess I never have been sure about whether you are supposed to crank the engine until the needle stops moving or just for a set period of time?

I've got a lot of maintenance experience on various rigs, but haven't taken on much in the way of larger projects before, so I'm just learning on the fly right now. Thanks to everyone again for their help and knowledge.

DudeBud

turn it over until the needle stops

yzrider273

HOLY S@&T!!! that's what's happening to my 86 4-runner
..the 100 miles per quart
..slight oil mists coming from the exhaust on startup
but im hopefully starting to think it might be a valve related problem