4g54 2.6 Astron

[Johnnymac01]

Gday lads,
Got a mate that seems to have snapped his timing chain in his Pajero 2.6 1986.
Is the 4G54 an interference engine? Everything I can find indicates it is not, but want to be sure before he puts it in for a (broken) chain change.
Trying to figure out if his valves will be shot.
He parked it one day and then half an hour later went to start it and it wouldn't.
RAC found that the dizzy wasn't turning!
I've never seen a timing chain snap during start-up or switch-off - but guess it's possible.

Did search the forum for this info (and half the intermenet google thingy!) so anyone that can confirm for sure would be thanked muchly.

JM

[A112H]

First thing I would be doing is removing the dizzy, sounds more likely to me that the drive gear at the end of the dizzy has sheered it's locating pin.

[Johnnymac01]

Good call!
Did take dizzy out, and all's good on that though. Would've been nice....
Anything else it might be, besides the chain? I assume that the cam gear that runs the dizzy is possible also?
Thanks heaps for your help lads.

JM

[GB_BB4C]

Remove the rocker cover and see what ya find. The camgear bolt could have come loose or ya might see something happened to the chain...

[Johnnymac01]

Yerp. Cool. Will do, thanks heaps.
Does anyone know though if it's an interference or not? In any case as the cams not moving (checked in the oil filler) it'd be good to know if the valves might not have been buggered before we spend too much money on it.

JM

[dvsfin]

yes, I am pretty sure they are interference

[Superscan811]

At a guess, I'd agree with dvsfin.
10mm of valve travel standard = Approx 8mm vertical travel.

Piston is less than 0.5mm below deck std.
Head gasket is 1.3mm thick when compressed.

Doesn't leave a lot of room for the valves to clear the top of the pistons.


Cheers.

[Johnnymac01]

Thanks heaps for the replies lads.

I really do need to know for sure though.
I've got a bunch of forums/websites that seem to indicate it isn't interference - but once again, none are definitive:

http://redlinegti.com/forum/viewtopic.p ... &view=next
http://www.turbo-mopar.com/forums/showt ... -TSI/page2
http://www.cb7tuner.com/vbb/archive/ind ... 68427.html
http://www.aussiemagna.com/forums/showt ... hp?t=72801

I guess I'll just have to check under the rocker cover first for obvious valve probs, then run compression tests in the cylinders and see if they pump up. That or actually take the head off!

Wish I had an endoscope!
Thanks again.
JM

[75wagon]

Wow, the blokes at RedlineGTi.com speak highly of 2.6 Astron motors don't they

Dave...

[dvsfin]

the one's talking lowly of the astron obviously have no idea what they are talking about.

it might depend on what series and model astron you have too, when I pulled apart my astron 2 (out of a gj scorp) I noted that there wasn't much room between the valves and the pistons as I was contemplating leaving the valves in whilst milling the head LOL I obviously didn't, I was just tired and being lazy

[81GL]

the one's talking lowly of the astron obviously have no idea what they are talking about.

Got that right...

it might depend on what series and model astron you have too, when I pulled apart my astron 2 (out of a gj scorp) I noted that there wasn't much room between the valves and the pistons as I was contemplating leaving the valves in whilst milling the head LOL I obviously didn't, I was just tired and being lazy

And was about to say the same thing with it depending on the engine - and whether in its life there has ever been any work done, like a skim of the head etc.
Also, solid vs hydraulic lifters would no doubt alter things a bit too I'd imagine

[astronturbo77]

stop mucking around and pull the rocker cover off, wind the engine over by hand and see whats rotating, they are interface.

[geezer101]

Guys on speedtalk.com seem to appreciate them!

[Johnnymac01]

Thanks for all the advice lads. Would really appreciate some more if you have time.

Managed to get out to my mate's place today and ripped the rocker off. Timing chain is gone.

Did a careful check on rockers and only one was even slightly loose (about 1-2mm at guess). Then did a very careful compression test on all cylinders and this cylinder came up no compression (all others OK). Bugger. Seems to have buggered a valve.

I have a couple of questions cos he really doesn't have much money, and I really don't have the skills or time to help much. Any advice would be very welcome, thanks.

- how possible is it that the piston is damaged in that cylinder? If it isn't he'd really like to not have to replace the whole engine! I know I can pull the head off, but I really don't want to have to do that before he can make a call (on fixing the car or selling it as is) and get it into a mechanics. I really don't have time to pull a head off, so am interested to know if it is likely that the piston can be damaged. He can gamble from there if necessary and put it into the mechanics, who may even then still find that it is.

- is it possible (or even worthwhile) in getting the head pulled off and changing out that one valve and dropping the head back on? I know there's a fair bit of labour still, but might save him on a whole new valve set and setup and head face, etc. Once again, just trying to weigh up the projected cost so he can see what he can afford.

- If he does need to get a whole new set of valves put in - approx how much are they worth and what would be a reasonable cost for the fitment to his existing head? Would the head need a recon? Or pop them in and seat/lap them (or whatever the term is!)

Thanks for any advice lads. Sorry I'm being so particular - he's got a lot of questions and wants to be fully aware of the situation before he spends any money - with minimal surprises. And this head stuff is a bit out of my league, but I'm trying to help him as much as possible!


JM

[75wagon]

Best thing to do is take the head off and look.
It should answer a lot of questions for you.

Any suggestions on how much damage or how much it would cost to fix would be pure speculation.

I have had a valve drop before and did no damage but to bend the valve. I took oversize valves out of another head that I had that was corroded and had them fitted. Cost about $200 or there abouts to have the head reconditioned with the valves fitted.

Dave...

[Johnnymac01]

Thanks Dave.

I'm not really looking for speculation - only experiences like the ones you've supplied. So thanks heaps, that helps. Even a "pistons not damaged in my experience", or "I got my head recon for $200" is better than nothing.

I won't be pulling the head off, but even if I did it wouldn't help me with the second and third questions - can you swap out just one valve, and will the head def need a recon just cos it's pulled off - or can you easily get by without it?

I could ask these questions of a mechanic, but I would trust someone on this forum more! The first mechanic he took it to heard that the dizzy wasn't spinning (didn't even check), told him he needed a new engine at $3000+, and charged him $60.

Appreciate any experiences.

JM

[75wagon]

Yes you can change one valve.

No, the head will not definitely need reconditioning if it comes off. But you will need to make the new valve seat properly. You could use valve grinding paste.

It wont be a performance fix, but it would work.

But you need to see it the piston is damaged before you do anything.

Dave...

[dvsfin]

I suggest you stop piss farting around and hoping someone on here is going to solve all of your problems for you and just take the head off, what do you have to lose by doing it? It's not that hard pull apart and see, either way it needs to happen anyway.

[astronturbo77]

stop pulling your dick, pull the head off instead, have a look use your eyes, head gaskets are under $50, if you have no idea you shouldnt be playing with cars.

[Johnnymac01]

Thanks 75 Wagon. That is what I needed to know. You're a legend of a forum member.

As for the rest of you. I've never met a forum of such arrogant f_ckers in all my life.

If I was a f_cken mechanic I wouldn't need you. I told you I wasn't going to f_cken pull the head off. It's not my car, I'm trying to help out a mate I don't know that well without it costing me hours in time, I've made that very clear. What do I have to lose? My f_cken time and investing in a project that I don't have time and he might not have money for. Why do you have to try and second guess my position and bag me for it? Why can't you just f_cken answer the questions? Is this a forum or a f_cken rite of 2.6 Astron passage?

You elitist bastards are all happy to pull off heads to see what's wrong, great. But can't you just help someone with innocent questions who is tryna help someone else and doesn't want to f_cken pull a head off? You have to abuse them with comments like "stop pulling your dick?". I have pulled heads off smart d_ck. I have changed engines over. I do not want to f_cken do it to this car that is not mine and I hardly know the guy. I'm tryna help him make a decision and save him some money. If any of you c_nts were half as benevolent you might do the same.

Rot in hell with your f_cken 25 year old shit engines that you think you are king of and don't want to share knowledge with anyone else.

And delete this post if you are a f_cken pussy and can't stand by the result of your arrogance.

Nice way to get people into the forum...not.

[A112H]

You say you have the rocker cover off, can you see any issues with the valves? If it has dropped a valve into the cylinder that has no compression then I would guess it has holed the piston, you should feel the air coming out through the valve hole in the head on that cyl.
If you can't feel anything there, take the dip stick out and crank the engine over with your finger on the dip stick tube, see if it is pressurising the sump at all. The displaced air has to go somewhere.
But I gotta say, for the sake of 2 hours work and a $50 gasket, I would have pulled the head off. It isn't drivable so will need to be towed wether it goes to the wreckers or mechanics, won't matter how many pieces it is in either way.
You will only get a full idea of the damage by removing the head.

[81GL]

I'll take offense to that (*throws it in the pile*)

Understand where your coming from with just wanting some experiences from others encounters. But what astronturbo77 & dvsfin were pointing out (if not a bit abruptly guys...) was that when it comes to working with cars; unless your dealing with a known common issue, others experiences are not really going to give you a clear answer of what may be wrong with your (/friends ??) car. Removal of the head would be the 'preferred' sure fire way of knowing what exactly has happened in there...

Anyway, back to the car... Yes, providing everything else is undamaged, replacing a single valve will get the engine up and running again. I've had this done before when a valve burnt and lost compression.
And there should be no need for a skim of the head as it hasn't blown a head gasket or the likes, just get them to double check it is with in tolerance when/if the valve gets replaced.

Just another option, is the engine an Astron 1 or 2? (does the oil cap screw in or push in?), if screw in, then astron 2. If Astron 2, you may also like to look around for a complete second hand head from a 4G54 magna to be used as a replacement assuming the bottom end is all okay. There will be some mucking around with the rear water gallery being a front wheel drive engine, but if you find one at the right price could be a "feasible" option if on a budget.

Good luck with it all.
Nick.

[Johnnymac01]

Thanks for the extra tips and advice guys. That's the sort of experience sharing that forums should be about!

Valves stems looked fine and are operating fine, except the one that has a bit much clearance. I'm guessing that it has just bent so valve won't seal properly - or snapped the head off and the bent end of stem is stopping the spring pulling it out of the guide. But will have one more look to try and ascertain extent of valve damage. "Feeling" the piston face with a bendy plastic probe through the plug hole is something someone else has also recommended, so will do that. Will also check for sump pressure, thanks for that tip.

Now I have a better idea of the probabilities and possible actions, if all points to single valve damage and no piston damage at next cursory inspection I will advise him to tow it to a mech and get the head pulled and the dud valve and chain replaced - should be well under $1500. He can deal with any scary surprises at the low end of the gamble regarding pistons, head damage, etc., if and when they show up. If I can prove that the piston is damaged I'll recommend he source a used working motor straight away, or sell the car as a licensed "project" with known issues. He can't afford a new $3000+ engine, and frankly I don't think the car is worth spending that on. But a $1000 or so changeover might be worthwhile.

Thanks again

[dvsfin]

I take offense to that, I was just saying the head has to come off either way so just take it off already, you can't see the damage until it's off and there is no way to fix it without taking it off. You or him have nothing to lose as the car isn't running anyway, once you take the head off you will know what's wrong then you can ask questions about how much it will cost. The timing chain isn't on and you had the rocker cover off already, it's not hard. In the amount of time you have taken to type all of these pointless posts you could have had the head off and diagnosed the problem yourself. I don't see how we are being elitists or arrogant, you are expecting us to tell you what is wrong with the motor from experience? When you won't know for sure until the head is off and it NEEDS to come off anyway.

I am not being abrupt or rude, I am just telling you straight forward what needs to happen as there are no other options you have. I don't understand what you are hoping to hear on here anyway? Some magic answer that will fix everything? It's quite obvious that there can be no real help until that happens and you see the extent of the damage.

All I have given is real answers, if you don't like them then don't ask the questions.

If you want speculation then fine, because the chain has snapped the motor would have almost stopped dead depending on revs, meaning the damage would be minimal, maybe a bent valve but then it could also be a lot worse. Holes in pistons and other major damage to the head or cylinders usually occur when a valve drops and the engine keeps running on the other cylinders which constantly smash the valve into the head.

But hey it could of even cracked the head depending on the conditions.

[Johnnymac01]

You gave me NO answers mate. You said "I suggest you stop piss farting around and hoping someone on here is going to solve all of your problems for you and just take the head off, what do you have to lose by doing it? It's not that hard pull apart and see, either way it needs to happen anyway"

If I have to point out what's rude about that you aint been brought up right.

I don't have to pull the head off smarta$$ - if I prove that the piston is shot without it I won't have to drag all my tools to someone else's driveway and waste 2+ hours of my time on a car that I'm not familiar with that's not mine.

If I can prove the piston is not shot I still don't have to pull the head off cos I'll tell him to get the mechanic to do that - a mechanic who he has to take the car to anyway.

If I drag all my tools to someone else's driveway and spend 2+ hours taking a head off and find the piston is holed I HAVE WASTED MY TIME COS THE ENGINE IS NOW ROOTED.

Do you get it now? Is this evidence of "other options" enough for you?

I never asked for a "solution" or "magic answer". I asked specific questions which others have managed to answer (without it being "magic") that you couldn't be bothered answering. If you don't like helping people - don't answer threads on forums. I did the right thing and searched for existing answers - so either ignore my posts or actually help. You chose to ignore my questions, but only offered rudeness in return. What is the point? Are you just a rude c_nt and enjoy showing other people that you are? Or in some way did you actually think you were helping me in your own, twisted, rude way? I'm a new forum member, do you think treating me like $hit just cos you've been on this forum for some time encourages people to continue with this forum? Do you think it's good for community building? Do you think it's going to make you friends?

Even your reply at the bottom of your text, which is trying to finally help, shows that you haven't actually read my posts properly. The chain either snapped on switch off or start up - so the motor would have hardly been spinning. That is, not likely cracked head and motor barely turning over. But thanks for your experience on holes in pistons. That's actually the sort of thing I've been looking for.

You are not a facilitator mate. You should refrain from pretending that you want to help people and just post posts about yourself and what you're up to. That seems to be all you're interested in.

[A112H]

Sorry guys, in an attempt at stamping out a growing fire I will have to lock this thread.
I believe the original question has been answered as best it can anyway.
If anyone has issues with this feel free to PM me with your concerns.

Cheers