Engine Rebuild Problem. Smoking! Need Help!

[jtsarnak]

Warning: I know this is long, but it has a lot of information that may be useful to solving the issue at hand, so if you're interested in helping, I only ask about 5 minutes of your time to read all this.

So, here goes the story of what, right now at least, is a 7 month disaster.

I decided at 130,xxx miles it was time to rebuild my engine, which is out of a '95 so it's a KA24DE. Nothing really wrong with it, but turbo dreams were in the future and I really wanted to learn a lot about my car & engine before modifying it. My brother had done his big block Cadillac engine the year before and while the KA is a totally different beast, with his help and the FSM we decided to go for it.

I ordered a complete rebuild kit from TopLine, we pulled the engine in a weekend and tore it down over the course of a few more weekends, learning the in's and out's as we went and making sure to label everything or take pictures so we could remember what we were sure to forget.

Once we had a bare block and a removed head, we sent them off to the machine shop who rebuilt the bottom end using the rebuild kit and did work on the head. The shop reassembled the block internals (pistons, rings, rods, crank) and the head (valves, seals, springs, etc). We picked it up a month or so later and began the rebuild process.

For the most part, the rebuild was easy. Everything went together pretty quickly and the only rough spot was the timing chain and camshaft assembly. We found initially we did it wrong when we tried to hand-crank the engine and found resistance at the same point in every revolution. We realized our mistake was in the timing and that the valves must have been meeting the piston at top dead center. Let me tell you that it is the timing where the FSM really is very vague and unclear.

We used the old chain and gears as a guide to resetting the upper chain when the engine was cranked to top dead center in cylinder 1. I think this later becomes a problem because the lower chain may not have been lined up the way it was supposed to, but I have no idea because the lower cover was already installed. All we know is using the old chain as a guide, we cranked the engine by hand and got everything to revolve without a bit of resistance.

We get the rest of the engine together, replacing the water pump and thermostat as we go. We the drop it back into the car 2 weekends ago. It took longer than we expected because dropping the engine in and getting it to line up with the transmission at the same time was a huge pain. So it was hanging by the head from the hoist for longer than we were really happy with and we prayed for the head gasket to still be happy.

We get all the wiring done, all the belts done, all the piping done. Everything is ready to go. All we get is cranking, no firing. We have spark. We definitely have fuel (it smells of it). We racking our brains for over an hour trying to figure out why. We then decide maybe we had the timing off and everything is backwards so we flip the rotor 180 degrees. Starts right up! We had it firing at the wrong time. But its running and with some twisting of the distributor, we get the timing to where it isn't great, but it's acceptable.

Here is where we notice it is smoking. Now it doesn't smell terrible like oil so we figure it just may be assembly lube burning off. It continues to smoke. It smokes longer than I'm happy with and the radiator isn't draining so it appears that coolant isn't passing into the block. We turn the heater on, but no hot air is blowing and the temperature gauge is rising so we kill it.

And that's where we are now. I had it towed to the mechanic and they indicated that the valve timing is indeed off. They say the upper chain is not set up correctly with the lower chain and they will have to remove the front cover in order to set it right. Book time is 12 hours which is about $1000 in labor. I have yet to give the go-ahead because it is smoking.

So, here's the scenario: Compression test shows 220's & 230's for the first 3 cylinders and 188 for the last. I feared a bad ring (hence the smoke) in the last cylinder but my mechanic says that the first 3 cylinders are high and the last cylinder is showing a relatively good number. He believes the timing being off is causing the high compression. But that doesn't explain the oil burning (which we determined at this point is definitely oil burning).

So I ask what it could be. A bad ring, which is the fault of the machine shop. Bad valve seals, again the fault of the machine shop. High compression may lead to blow by, the fault of the timing but not guaranteed to be the issue. I asked about a blown head gasket being it was hanging for longer than expected, but they didn't seem to think that was the problem.

So this is my story and my cry for help. If anyone has any ideas or advice, I could use it. It's a $1000 guess to see if the timing is indeed the be-all, end-all culprit. If not, it means tearing it all down again and more money down the drain. I would not like to have to do it myself as I am getting married in 8 days and no longer have easy access to a garage or tons of time to work on it, but it may come down to that.

So, if you have ideas about where the oil is coming from or any other issue, no matter how weird, I'd love to hear them. If the evidence at hand points in a certain direction of the problem, I'd love to hear. If you're really good with a wrench and live near Monmouth County, NJ (I'm in Howell, near Jackson, Freehold and Lakewood) and want to offer your assistance, I'd more than welcome it. I just feel like I don't know what to do next and other than the timing issue, feel like we did everything else right. I just don't relish the thought of spending $1000 in labor charges to hear it all needs to be torn down again. Thanks in advance!

Modified by jtsarnak at 3:46 PM 9/9/2004
Modified by jtsarnak at 3:50 PM 9/9/2004

[Twinchy]

hey man your story is too long i gave up on the second paragraph

[jtsarnak]

Thanks for your help then.

It's long because the problem is involved. If you have the mechanical know-how to help, the read is necessary because it gives all the clues to where the oil is coming from that is burning. If you don't, please don't respond by saying you didn't want to read it. That offers me no help at all. Besides, it's like less than 5 minutes of your time to read and it could really help. Thanks in advance to anyone willing to give me a hand.

[toptechracing]

Ok I see it is a DE. My guess is you have the early piston in a late motor which would give you about 230 PSI cranking. That would be the fault of the supplier. The hole with low compression is probably a tagged valve from having the cams set wrong. The smoke is probably because you have not run it long enough to seat the rings. The rings in the KA are very difficult to seat and running the motor hot and with improper timing will make that harder.

Joe

[jtsarnak]

My fault, all of that and I didn't say DE or not. It's a DE out of a '95. I edited the top post to indicate that. Thanks.

[Ubernoober]

Ouch, tough luck. Rings in a KA are no harder to seat than in any other engine. You have too many issues for me to recommend paying the shop an additional $1000 to fix what may or may not actually be the problem.I would take the engine back myself and pull the head/front cover to see where you stand, but you mentioned you do not have the space or time. I don't know where to go from here, but giving away a grand for something that might be ok is just too much.Go through your reciepts and see if you indeed have an early piston. The supplier may have goofed as Toptech mentioned. Rings seat quickly. A little smoke is acceptable until you put your first running load on the engine/rings, but considerable visible smoke is not good. Bad valve timing cannot raise static compression, it can only lower it. I really don't like that you think you contacted the piston with the valve even while hand-cranking. That would worry me.If I can think of anything positive to help, I'll be back. Sorry I couldn't help more.

P.S. Twinchy, could you possibly BE more useless? Hell, you're less than useless.

[jtsarnak]

Thanks for the replies so far!

I checked the receipts from Importperformanceparts.net and the topline kit item # matches the one on their website for a 95-98 240sx KA24DE, so unless they packed the wrong pistons in the kit, which I have no idea on how to tell, I believe the pistons are correct.

The mechanic told me incorrect timing on the cams could make it so there is not enough valve overlap in the compression stroke and thus it's very possible to get a higher compression rating than usual. He told me normally there is some time when both the intake and exhaust valves are open together and that this is normal. If the timing is off so that there is no overlap like that, the compression may actually go up. Any thoughts on this?

My thinking thus far: Oil is burning. Assuming the block isn't damaged, oil only comes from above the cylinders (aka the head) or from below (past the pistons). The smoking is constant enough to indicate that it isn't just a single cylinder that is burning (else you'd get more of a puff effect). The plugs also do not show one plug being more fouled than the other 3. So this leads me to believe either all cylinders are burning or at least 3 are.

If the oil is coming from above, it's either a blown head gasket or bad valve seals. Since it appears to be in the majority of the cylinders, it's unlikely that every valve seal is bad.

If oil is coming from below, either all the piston rings are bad (unlikely), they are all not set yet or there is blow-by because in the 3 cylinders with high compression.

If I pay the $1000 to get the timing right, they need to lift the head off, so the gasket can be checked easily enough. I'm assuming the valve seals can be checked pretty quickly too if the head is off. If, after getting the timing right and checking the head for the cause of the smoke, there's still smoke, then it's likely coming from below, in which case I think I can try to run it a while to setup the rings or take action against the machine shop.

Any further thoughts are welcome, because my logic may very well be flawed.

[yellow_jacket]

You do not need to pull the front cover to set the timing correctly. Just put the crank pulley at tdc and take the upper timing cover off. Then check the clock position of the cams. If you ask nicely I'm sure someone will email you a pic of how it is supposed to look. I would be more than happy to do it myself Saturday night. I have my spare motor sitting on my engine stand in my garage. The upper front cover is already off. This will NOT raise your compression.

Have you smelled the smoke? Does it smell sweet? How many miles have you driven this since you rebuilt it? Was the head blown before you rebuilt it? Have you had the throttle body off? Are you sure the throttle body isn't leaking into the intake? I definetely would not pay that shop $1,000 to check the lower chain. You have more than enough resources here to figure this out.

[yellow_jacket]

And it sounds you didn't get all the air out of the cooling system. Either that or you have a blown headgasket on #4, which may also explain the smoke. You really need to run this longer though.

[drftnassmofo]

hey...sorry to jump ryte in w/ my own probs. but, yellowjacket, if you get the tyme and do take those pics to set the timing can ya e-mail those to me too b/c these azzholes want to charge me at least $630 to install a new timing chain and i might not even need a new one..it could be a guide or suttin else..my emails [email protected] if ya get a chance, thanx..sam

[jtsarnak]

Sorry to resurrect this thread, but the issue has been resolved and I figured for an education, people may want to know what was going on.

I got back from my honeymoon late last week to find the car was all done at the mechanic I took it to.

They redid the cam timing and had to get to both chains in order to do so. It turns out that the timing was off such that a vaccuum was essentially being created on the compression stroke with the exhaust valve being overlapped too much. This is what was causing the high level of smoking, it was basicaly reburning a lot of exhaust.

The timing is now straight and it still smokes, but it's 95% better. I'm assuming the smoke is break-in related as it has less than 100 miles on the new engine. It only smokes (and even then just a little) when I really punch it so I'm going to give it a couple hundred miles or so.

I just thought everyone may be able to learn something from my nerve-racking experience.

[corn322]

so what was the deal with the 230 psi compression? did they accidentaly give you sohc pistons?

[driftaholic]

with sohc pistons i get about 225-230psi. weird eh

[Altiman94]

Where did you get this rebuild kit from? Im rebuilding a de also.