engine rebuild - rust in cylinder

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oldn64
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Re: engine rebuild - rust in cylinder

Post by oldn64 »

antus wrote:We got the pistons back in last night. This is the first time we've done this but so far, so good.

The piston here is one of the spares, it didnt end up in the engine.
First time you have built an engine...? wow what a great start.

secret to having this done right antus is to disassemble and measure multiple times to make it right.

Have you balance the rotating assembly?
have you measured your bearing clearances?
do you know the rotating drag for the crank?
have you measured your ring gap yet?
what assembly lube have you got?
are you going to coat the headgasket?
is the headgasket a MLS?

ask questions, i could do thid with my eye shut.

Cheers
oldn64
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Gareth
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Re: engine rebuild - rust in cylinder

Post by Gareth »

According to chemistry, alcohol is a solution...
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antus
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Re: engine rebuild - rust in cylinder

Post by antus »

Well its actually the second time. The first was 10 years ago, i own it 50%, and to this day its still sitting in a mates shed. It turned smoothly at the end of it, so I think it was good, but ive learnt that engines left sitting for 10 years dont necessarily stay perfect. If this one turns to shit, I think i'll recover the other one (its a 4ze1 2.6L) and go with that instead. Its the back up plan.

This engine was supposedly already rebuilt, and the cleanlyness, except for the rust validated that. Also the numbers in texta on the pistons. There was still engine assembly lube in it too. The problem was that it had seized from getting water in it in storage, and we had to dismantle it to get it moving (no amount of oil or force on the crank would free it up). Also due to lack of parts availability, im pretty happy to replace nothing and just want it back together and working.

The new problem we face, as that after we tightened down the crank and the pistons, it siezed up again. The bearings were ok (not new), and now we have relised that we never saw this engine turning and wondering if I was sold something with issues over 10 years ago when I bought it. The next thing I need to figure out is which bit is jamming, and why. Perhaps some of the bits have been swapped around in this engine, or from another. The more I think about it, the more I think i have been facing a hardware problem that was not rust from the beginning.

To answer the questions:
Have you balance the rotating assembly? No - running with what it is
have you measured your bearing clearances? No - could be very relevant, i'll research this.
do you know the rotating drag for the crank? No
have you measured your ring gap yet? Yes - its above the recommended spec from Holden202Ts post (approx double whats listed), but since I dont have other rings (I had G200Z rings, but they turned out to be too thick) and since it was supposedly running before, Im planning on running with the rings as they are. I dont think i'll have the problem with the gap being too small. Some blowbye is acceptable.
what assembly lube have you got? Some tube of "engine assembly lube" (I could go out to the shed and check, but if the question was do we have any and are we using it - yes)
are you going to coat the headgasket? Probably yes, havnt thought that far ahead. Used hylomar last time I took the head of my other G200W (not counting that as a rebuild)
is the headgasket a MLS? I do have an MLS, but if this engine starts looking too iffy I think i'll put a regular one in to see if this engine is even worth persuing.

I do love the G200Ws but im getting old enough to care less what type of engine it is, and more about not wasting too much time. The 4ZE1 will have 600cc more capacity and still be isuzu thus being eligable for most competition events in this car. Also parts are far more easily available. If it ends up going that way I'll keep this and the other G200Ws as spares for the road car.
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Re: engine rebuild - rust in cylinder

Post by delcowizzid »

Don't have the bigends caps all messed up they can only go on there original rod and only around one way .if someone's previously just taken all the caps off and then fitted on random rods she will lock up .normally torque all the mains check it turns then one by one fit and torque each piston and rod making sure it turns after each one before fitting the next one
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oldn64
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Re: engine rebuild - rust in cylinder

Post by oldn64 »

Great summary Antus,

you essentially answered all the questions spot on... :thumbup:

So now to the help.

to diagnose you will need to pull the motor down again. Remove all pistons and rods (dont drag the rod down/up the bore or across the journals on the crank.)

with the crank in the block and torqued down does the engine turn? if it doesnt then it is crank and block related. otherwise we now need to find out what has happened with the pistons. goto next step.

install two pistons (their pairs.) so not cylinder 1 and cylinder 2 you will want 1&4 and after those are checked pulled 2 & 3 go in. rotate after each assembly. You will need to verify the where the issue lies. I would assemble with molybond initially, this will keep lub up to the parts and allow you to diagnose. I would also coat the pistons and remove the rings. (removal of rings is a little dangerous as if they have run before they can be fragile. this is only to determine whether you have a journal issue piston issue or ring issue. If it locks up during the piston processure you will then need to find out which one. Do not assume there is only one. when you find the ones that are problematic remove the piston and bolt it down sideways with the block upside down, this is to rule out the piston and that it is the journal big end. if this is all good then look at the rings. fit and retest.

I suspect you will fail on step one, maybe step two. If failure on one then the crank might be bent or the block mains are not inline or the caps have been mismatched. undo one cap at a time and retest. if still locked then retorque that cap and try the next. This takes time. Now the fun thing.

MEASURING.

measuring you journals and bearings the right way means the use of calipers and verniers. take the crank out and install all bearings in the caps and block and torque. using the calipers find the size of the bearing and measure the caliper with the vernier. do this on each journal and measure in at least 4 spots. note all of it down. then use the vernier to measure the crank journals with the same measurements as what you did for the block. ideally the crank journals should be 3 thou smaller roughly than the block. if not the bearing will crab the crank. if you cannot find verniers or calipers there are two other options (I would normally use micrometers but these are specialist tools whihc you will nto just go buy for one build.)

go get yourself some plastigauge. This is not 100% accurate but will give a good guide. I have used this before with good success

engineering blue - it is like a paint, spray on the bearings lightly place the crank in torque up and then undo. Do not turn initially as you want to have transfer. where there is blue on the crank is potentially a tight spot. it sort of work in an absolute pinch. (must be done without lube, and the second time you go through this you need to turn the crank (if you can) slowly to show the tight spots, it should remove the blue off the bearing.


now if none of this can work pull the bearing and on the back it will display the size of it. usually as a 20 30 40 etc this is thou and for mains and big ends it is under size. If you have put 20 thou under but it is a virgin crank then you will have at least 17thou clamping your journal and thus the reason it does not turn. Verniers should be enough to tell you the journal size of the crank and big end journals which should be able to calculate the approximate gap. this will not find out an out of round journal or bore but it will give a indication as to whether you have the right bearings, crank and pistons. You might find a rod has been change and it is different to the rest. Generally the cap need to stay with the rods too, if you swap them this can cause an out of round, thus step two should find it.

More information to follow once you know roughly where the issue is.. above all good luck antus!

I know where you are at currently as I have help many others who are in this issue, but it should be possible to resolve. (if the category is IPRA then why not serious look at the 3.2 out of the rodeo... nice v6 running a delco with buckets of torque :D :twisted:

cheers
oldn64

ps delcowizard beat me with a short answer, mine will help you find the issue. if it is rod related then we can try swapping them, but keep everything together to start with ;)
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