Piston Soak?

[88Adventurer]

Tried to find this info on the forum. My 88L has no basically no power in cylinder 4, getting a lot of blowby into the carburetor. Has anyone done a piston soak with Sea Foam? Good results? And exactly how would you go about doing this? Thanks for any info.

[Dave G]

If it's blowing back into the carb it's an intake valve problem.

[mechanicaldj]

do a wet and dry compression check

[darkdan]

Seafoam will do a decent job for a piston soak.

However, a stronger solvent should be used IMO.

MMO would be one step up. Something like B-12 Chemtool would be two steps up. LC20 by www.lubecontrol.com would be good.

A deep cleaning with www.auto-rx.com would be a good idea too. You can use coupon code ARXDD for a few bucks off. It will safely and thoroughly clean your ring packs.

However, it could be worn.

Before and after compression checks would be nice.

Check out the compression numbers on this test:

http://www.auto-rx.com/rms13/

[88Adventurer]

Been reading up a bit on this. Could excess carbon buildup cause low compression? Did a compression test last week but I don't think the engine was warmed up enough to get accurate readings. And could a Sea Foam treatment actually make things worse? Like maybe there's some sludge in there that's holding things together? I'm currently using Auto-RX and noticed some really dark oil coming out when I changed it last. Seems to be using more oil now. Just wondering if this might be beyond an engine cleaning and a rebuild is needed.

[Dave G]

Been reading up a bit on this. Could excess carbon buildup cause low compression? Did a compression test last week but I don't think the engine was warmed up enough to get accurate readings. And could a Sea Foam treatment actually make things worse? Like maybe there's some sludge in there that's holding things together? I'm currently using Auto-RX and noticed some really dark oil coming out when I changed it last. Seems to be using more oil now. Just wondering if this might be beyond an engine cleaning and a rebuild is needed.

I think if you give more detailed info on what it's doing you'll have better luck getting advice.

You say it seems to be using more oil - sounds like you're driving it regularly. How's it run? Any idea where the oil is going? Out the tail pipe as smoke? Into the cooling system?

Earlier you said you were getting blowby into the carb - what does that mean, exactly? What are you observing it doing to make you think this?

If you've really got super low compression in one cylinder then I'd say the thing to do is pull the head and see what's going on. Repairing whatever it is that causing the low compression almost certainly requires pulling the head, so it's not like you'll be wasting time :-)

[packrat427]

My Caddy Northstar eats a MAP sensor every 6 mos. Cadillac was replacing them under warranty for the last 3 years , The last time I had it in there , they said we found the problem "blowby" ???
I see no visual blowby , no smoke out the exhaust .
They said the blowby was contaminating the MAP sensor and making it fail .
They found this out from many other's with the same problem ,thru the GM tech's.
They said this can be fixed with a piston soak with a machine that GM has that sprays in like a injector , they let it set overnight , run it , and repeat this process ,to free up the ring pack and create a tighter ring to wall fit , thus eliminating the miniscule amout of "blowby " that is messing up the MAP .
They told me that Seafoam would work just as good ,Giving it a healthy dose , almost flooding it with it then shut it off , letting it set ,repeat as necessary .
So far it worked on the Caddy , I do it to my Festiva often :lol:

[88Adventurer]

OK, when I did the compression test, the dry numbers were 110, 20, 32, 21. Wet test was 115, 20, 40, 25. Don't think the engine was up to operating temperature, took a five minute ride before using the guage. I'm assuming blow-by because the oil is going into my carburetor, good clean oil there because I have to add oil daily. I drive about 100 miles a day for work. MPG is 22 - 25, on level ground it can run at 65 mph, going up small hills it will drop to between 55 - 63 depending on how big the hill is. Need to add between 1/2 to a full quart a day of oil. It runs a little rough until about 45 - 50 mph where the engine sounds better. I don't try to pass too many cars because it doesn't really have any passing power. It smokes lightly for a couple of minutes on start-up then stops. The oil seems to be going into the carburetor and running out on top of the valve cover. Had the head gasket done this summer, new/used head put on, no crossover. With the carb I have to pump it to get it started, but after a few miles it idles just fine. Packrat427, where is the MAP sensor on this Festiva? Think that could be the problem here? Thanks to all for the replies. Need to know anything else, just let me know. I'm not much of a mechanic, just trying to get this little car going.

[packrat427]

On 88-89 Festiva's ,the MAP sensor is by the firewall right behind the air control valve , which is connected to the air breather on the right side , looking at it from the front , should be dead center of the firewall.

[Dave G]

OK, when I did the compression test, the dry numbers were 110, 20, 32, 21. Wet test was 115, 20, 40, 25.

Yuck! What do the spark plugs look like? I'm thinking it's engine rebuild (or swap) time.

[88Adventurer]

OK, the spark plugs had no oil on them at all, but were kind of a white color. Still gapped as they should be, no distortion.

[Dave G]

OK, the spark plugs had no oil on them at all, but were kind of a white color. Still gapped as they should be, no distortion.

That's odd, given all the other things. The one in the cylinder with compression looks just like the others? Are you sure you're measuring the compression correctly? No leaks around the gage?

If the compression check is accurate, I'd take off the valve cover and check the valve clearance (I think I remember reading that the 88 has mechanical lifters, doesn't it?), and take off the timing cover and check the valve timing. (Opps, not in that order :-) ). If that is all OK, and/or adjusting those things does not get the compression back up where it should be, then you're going to have to pull the head and see what's up.

[88Adventurer]

Yeah, all the plugs looked the same. I want to drive it a little more this weekend to get the temperature up and retest.
I've been told to put in everything from automatic transmission fluid to Lucas Oil to get this leak stopped and get back some compression.
Had the head gasket replaced this summer, there had been crossover and since having it done there hasn't been any. Had the timing set also. What all is involved in checking the valve timing? Don't have my Haynes manual handy. And if it's off could that explain losing oil? The carburetor seems to be soaking it up.
Trying to get this thing figured out! Thanks for the replies.

[5.0zone]

Sounds to me like burnt or cracked valves.

Yes, 88 and 89 had adjustable valves/rocker arms, I only had to adjust mine once.
But if someone adjusted them too tight then that might explain it.
Checking the valve lash isn't hard. Just need to pull the valve cover and follow the steps in the shop manual.

[Dave G]

What all is involved in checking the valve timing? Don't have my Haynes manual handy.

Check that the belt is on correctly, that all the marks line up right. But I doubt that it could be off far enough to make it loose compression and still run worth a damn (and it sounds like it's running fairly well, considering).

I'm betting on tight and/or burnt valves plus a head gasket that's leaking like a sieve (into the oil passages).

Did it have these problems before the head was replaced? Did the problems start right after that?