best solution to cleaning valves and pistons?

[ill4na8na2]

Hi all,

Im new to this particular forum i couldnt find a direct answer in my search so my apologies if thier happens to be another thread on this somewhere. I was wondering what would be the best product to clean valves and piston heads with. Reason i'm asking is i bought my 91 300zx a couple of months ago and i bought it not running. It only has 88k on the clock but it has sat for the last 5 years without the upper intake on it. Even though for that time it was in a garage thiers still dirt, dust , and carbon build up on the pistons and valves. Im in the process of changing the timing belt and intake gaskets, mainly because it was already tore down to this point when i bought it and so that i can check the internalls since i already found a hose clamp that fell down in the intake. I havent removed the lower intake or valve covers yet i can just see a good amount of carbon build up and dust i guess down in the valves and on the piston heads. Maybe i shouldnt be too concerned with it i'm just not sure what to use to clean them since it isnt running at the moment. Any suggestions are appreciated.

[DCaff300ZX]

Welcome!
Generally if not needing lapping or other machine needs, shops would use a parts washing machine with chemicals to break down the soot and carbon if not too caked or distorted...with appropriate tools for the cleaning needs. As for fully cleaning valves and pistons further cleaning would be necessary and best performed with correct tools.
So for personal shop needs I'd (and I do) go with the various higher end cleaning products and a wire brush or less depending upon surface needs up until failure, if so looking for a shop close by that may clean parts for a small charge or even allow you to do so. I have a Z guy who I've used extensively over the years, and have created a relationship with him that has small benefits and you could try to do something like that as well.

[ill4na8na2]

Sweet i may have to go that route with it. I'm just trying to decide if its worth worrying about because its not horrible but enough that i can see it while i've got the plugs out and covers off. So i guess the second question would be is it worth going through the hassle or am i better off just putting it back together, get it started, then use some seafome or something like that?

[DCaff300ZX]

I personally would never consider trying to run a motor that's been sitting open for any long period, and especially that I've pulled a oddball part from the inside of. Quite possibly the motor is a junk/part motor given how casually and sloppily it's been cared for, or one pulled in favor of a fresher/known good one.
IF I was determined to use this motor, basically only a complete disassembly and cleaning of parts, inspection and measuring to determine their usefulness is totally necessary or you've wasted your time, then reassembly and compression tests...quite a lot more obviously than you seem to be hinting at doing or wanting to do. Without this however, I'd consider a VG30DE or DETT a ticking timebomb set at less than a minute or two.

[ill4na8na2]

Yeah i get completely what your saying. I wouldnt say its more than i was hinting at doing or wanting to do, i mean i have it tore down to the heads as it is, i just wanted to see if it was worth it or not to go through all that when i bought it not running, i'm just someone who hates to go back and do things over again because thiers something that i missed or goes bad after the fact. No this isnt the first time i've bought a car not running or one thats set for awhile, but it is the first that i bought one where a part of it was open, in my case being the upper plenum & Upper timing covers and everything was off an in a box that you remove to get to that point. Currently i have it tore down to the heads anyways, they just arent removed yet. I wouldnt say it was sloppily cared for as much as it was someone with no auto knowledge at all trying to get thier car to running. But the price, body and interior were right so i was willing to take the risk. I was planning on pulling the motor originally and doing as you suggested, then my buddy who has a 91 na was arguing with me to just see if it runs before i do anything. which is what prompted my question.

[itsa300zx]

When I had my engine on the stand, I poured a table spoon or two of ATF into the spark plug holes. Sat like that for about 6 months, cleaned the pistons really well of carbon deposits.

[DCaff300ZX]

Yeah i get completely what your saying. I wouldnt say its more than i was hinting at doing or wanting to do, i mean i have it tore down to the heads as it is, i just wanted to see if it was worth it or not to go through all that when i bought it not running, i'm just someone who hates to go back and do things over again because thiers something that i missed or goes bad after the fact. No this isnt the first time i've bought a car not running or one thats set for awhile, but it is the first that i bought one where a part of it was open, in my case being the upper plenum & Upper timing covers and everything was off an in a box that you remove to get to that point. Currently i have it tore down to the heads anyways, they just arent removed yet. I wouldnt say it was sloppily cared for as much as it was someone with no auto knowledge at all trying to get thier car to running. But the price, body and interior were right so i was willing to take the risk. I was planning on pulling the motor originally and doing as you suggested, then my buddy who has a 91 na was arguing with me to just see if it runs before i do anything. which is what prompted my question.

Gotcha...well, since things are disassembled to this point I'd definitely do as I said and be thorough with it if you really want the best results, and although understanding your buddies sentiment, I feel that circulating crud and possibly further small parts through the engine will not work out well.
Given the reasonable suggestion by itsa300zx, maybe try to clean out as much of the internals as possible, followed by a flushout of some sort with cheap oil and hand circulation where you'd feel any problems and stop, if that works and things look clean then maybe do compression tests on all cylinders and if good, use ATF for the old 1 minute run after that on power (if it starts) for a final clean and if it makes it through that, maybe you're OK. But I'd still be very worried, and all could be avoided by knowing which means disassembly of the rest of the block...especially since it's on a stand and already open, plus that band you found...

[ill4na8na2]

I appreciate the input. Yeah i think im going to tear it down and follow the factory service manual checks. Better to be safe than sorry.