Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

 
Old 11-23-2017, 04:30 PM
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Default Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

My question is about valve guides.

Compression is 200/180/180/205. Spark plugs coated in wet oil, wells coated in oil, and when I checked the pistons with a bore scope they had a nice wet looking black layer on them as well.

I'm already planning on the following:

Block:
.25mm overbore, hone, fresh pistons & rings
New rods & bolts
New bearings/bolts/studs/gaskets all around
Crank checked for straightness, possibly polished, balanced rotating
New water/oil pumps

Head:
Clean & Relap OEM valves
New seals
Re-use OEM guides, springs, retainers, keepers.

What is the likelihood that a loose/worn valve guide could be causing this? The oil contamination is mostly equal on all cylinders, which makes me think it's unlikely, but I'd like some second opinions. I'm basically trying to avoid spending much more in machine work, as everything besides the bore/hone I'll be doing myself.

Anything I should keep an eye out for when pulling the head that may tell me more? Besides the obvious like a bent or completely toasted valve lol. I'm gambling the engine's problem is elsewhere, just looking for some insight before tearing into it.
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Old 11-25-2017, 10:20 PM
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Default Re: Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

How about leak-down test? The basic thing when determining mechanical condition. Compression test is not the best method because it can still show quite good numbers while you have a lot leak-down. Is there remarkable blow by?

Originally Posted by Chance EG View Post
Head:
Clean & Relap OEM valves
New seals
Re-use OEM guides, springs, retainers, keepers.
Measure the valve stem to guide clearance, there is not any other way. Lapping valves is low budget method, and mostly in these days, unnecessary. Just clean them. If your valves and seat are worn, they need to be machined.
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Old 11-25-2017, 10:55 PM
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Default Re: Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

Originally Posted by JKaze View Post
How about leak-down test? The basic thing when determining mechanical condition. Compression test is not the best method because it can still show quite good numbers while you have a lot leak-down. Is there remarkable blow by?



Measure the valve stem to guide clearance, there is not any other way. Lapping valves is low budget method, and mostly in these days, unnecessary. Just clean them. If your valves and seat are worn, they need to be machined.
I have no idea why but I always forget about leak down testing.

There's actually almost no blowby that I can see. The intake plenum seems clean too (recirculated PCV).

This is a semi-budget build, but I'm also not trying to waste my time putting something together with a short life span if there's an easy option to beef things up. I'll check the clearances and the shape of the head/valves when I get it pulled.

Thank you!
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Old 11-30-2017, 08:29 PM
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Default Re: Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

if there's oil in the plug wells, that means the valve cover grommets are leaking, has nothing to do with the guides or valve seals. and if the plug wells have oil in them, of course when you remove the plugs the oil will run down onto the threads and tips of the plugs, as well as drop down into the cylinders onto the pistons. If I were you, I'd replace the valve cover gasket and grommets, clean the plug wells and spark plug wires out really well, install new plugs, and drive around a bit. Then check again.
Also, leaky fuel injectors can and will leave some liquid fuel on the tops of the pistons which will usually appear to be oil when looking with a borescope or even with a flashlight and the naked eye. just FYI.
Lastly, valve lash adjustment has a HUUUUGE impact on compression test results. A nd the valve lash adjustment is supposed to be done every 20k miles on a stock motor, and much sooner if the valvetrain has any aftermarket goodies in it. Do a valve lash adjustment (engine must be cold), install new valve cover gasket set, go driving for a bit, then do another compression test. you may be pleasantly surprised by the results
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Old 12-13-2017, 12:16 PM
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Default Re: Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

Originally Posted by motoxxxman View Post
if there's oil in the plug wells, that means the valve cover grommets are leaking, has nothing to do with the guides or valve seals. and if the plug wells have oil in them, of course when you remove the plugs the oil will run down onto the threads and tips of the plugs, as well as drop down into the cylinders onto the pistons. If I were you, I'd replace the valve cover gasket and grommets, clean the plug wells and spark plug wires out really well, install new plugs, and drive around a bit. Then check again.
Also, leaky fuel injectors can and will leave some liquid fuel on the tops of the pistons which will usually appear to be oil when looking with a borescope or even with a flashlight and the naked eye. just FYI.
Lastly, valve lash adjustment has a HUUUUGE impact on compression test results. A nd the valve lash adjustment is supposed to be done every 20k miles on a stock motor, and much sooner if the valvetrain has any aftermarket goodies in it. Do a valve lash adjustment (engine must be cold), install new valve cover gasket set, go driving for a bit, then do another compression test. you may be pleasantly surprised by the results
Honestly the more I tear into this engine the more I'm thinking you're right. I have yet to actually separate the head/block (really looking forward to doing so, just haven't had time) but the oil level never looked like it was burning or going down, there were no metal flakes/sparkles, etc. Took off the VTEC solenoid and the filter was clean as can be too.

I'll definitely be doing at least a light rebuild on this engine since it's out of the car, but I'm debating how far I'll actually go with it now.

Edit: Also, there were some decent sized aftermarket injectors on this engine... I don't know what they are, tried searching for PN or anything on the injectors that would indicate what they were, but couldn't find the info. I am POSITIVE those injectors at the very least weren't tuned right, and wouldn't surprise me if it was contributing to some of the black/wet gunk I was seeing too...

Last edited by Chance EG; 12-13-2017 at 12:43 PM.
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Old 12-14-2017, 02:31 PM
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Default Re: Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

That's possible. If the engine has bigger aftermarket injectors and wasn't tuned correctly, those pistons will be caked in carbon. Are you currently burning an excessive amount of oil?
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Old 12-14-2017, 02:43 PM
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Default Re: Preparing for Rebuild - Oil on Spark Plug Wells & Pistons

Originally Posted by pogeeboy27 View Post
That's possible. If the engine has bigger aftermarket injectors and wasn't tuned correctly, those pistons will be caked in carbon. Are you currently burning an excessive amount of oil?
Nope. Checked the oil before I drove the car home, and again 60 miles later and it hadn't moved at all. ECU is a "chipped" P72 but it was clear just by talking to the guy that he had no idea what tune was on it, or what the car was even running. He said it was an OBD2 ECU and it's not (which for me is a good thing, OBD1 P72 is more valuable).

I was suspicious in the first place of what was going on, but kinda jumped the gun on troubleshooting (or lack of) and pulled the engine because the car wasn't street legal to drive and I've been pretty choked for time lately on building. What else is new though lol.

Head will be pulled Saturday. At this point I'm willing to bet it's mostly caked fuel, carbon, and maybe just a smidge of oil that's on those cylinders. I'll post some pics just for the sake of it.

Since the engine is out I'll be doing a rebuild regardless, and building the head. I can still benefit from some stronger internals, and I'd rather not have to screw around with guessing games or pull this thing out again, so I'll just spend the money to do it right. Planning on revving this thing well north of 9K, so some work needed to be done here either way.
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