1992 tr 4 cyl

no sign of the collets anywhere

pictures say it all

camshaft bearing caps torqued down way above specs

stuffed camshaft, head ,and bearing caps ,:nuts:

That looks nasty, what does the green text in the last pic say :confused:

valve guide melted:)

going to put another head on it and see what happens

engine on the clock had done 260,000 km auto

failed no warning

car just purchased this week :doubt:
cause of failure
may have been the cam shaft bearings we tensioned way over spec

ceasing the cam --- cam stuffed--and cam caps

ouch...
pricey???

This is what happens when home mechanics that think they know better get hold of some tools :nuts:

is it really possible to overtighten the camshaft bearings?

Hey did you photograph my old head? :bowrofl:

yep the head will cost from $125 to $170

you have to buy the cam the head and the caps with the rollers

all have to match up

vrs kit on ebay 59

but what are flat top pistons doing in a 1992 TR engine block with a knock sensor and tr chains ???

the M6 head is tr

Whos engine is this Ray ??????

Whats the story :)

old fart
a new forum member not amc
young uni strudent
bought the car this week
no warranty , paid for own safety , and rego
starter failed then this happenend to him ................ all in the one week

failure at number two cylinder

car would not rotate a full turn -- pistons have survived and block bottom end ok

car looks nice now its at my place to fix it :cool:
using one of the heads you gave me old fart thanks -- helps the kid out
should have it running by saturday

If he needs any other bits gimme a yell and Ill check what Ive got Ray.

In ya last post, the left hand photo, there is a vacuum channel in the inlet manifold.

On Pooky's car that was almost blocked with goo from unleaded fuel.

The brake booster (which comes off that point) was getting vacuum ok but the blockage was making the car run like ****, guzzle fuel, stall occasionally and (believe it or not) made the auto trannie shift erratically and bang into 2nd.

I cleaned it out, wacked in a new gasket and everything ran sweet, including the trannie.

I got a gasket kit for the manifold which included the manifold gasket, thermo gasket, the gasket for the middle of the manifold, throttle body gasket and a couple of others for about $7 from autobarn.:shock:
The manifold gasket alone was that much if you got it separately. :P

thanks old fart

have the pleniumm apart and that whole brake vaccume channel was clogged with black goo
as you said

cleaned that out fitting new gasket

thanks old fart

have the pleniumm apart and that whole brake vaccume channel was clogged with black goo
as you said

cleaned that out fitting new gasket


Might be worth a mention in the first gen wiki :)

the wiki isnt being added too.....:cry: the guys are too busy

but that clogging can lead to a serious problem in brakes

might be only there if engine is sick or burning oil

so should be mentioned in the right places I agree

the wiki isnt being added too.....:cry: the guys are too busy

but that clogging can lead to a serious problem in brakes

might be only there if engine is sick or burning oil

so should be mentioned in the right places I agree

It also affects general running as if 1 side is blocked more than the other it makes the vacuum at each cylider significantly different.

In Pookys case the brakes were unaffected, go figure:nuts: (maybe she doesnt use that pedal lol )

That is one hell of a mess!!! :shock:

I'm going to suggest a possible theory about what's happened there: I reckon this is only half related to the overtightened cam bearing shells though. Overtightened bearings will cause some issues with the valves not completely closing and allowing leaking around the valve due to the rocker arms forcing the valves open slightly all the time. This causes buildups to form furthering the distance the valve is jammed open, and further strains the valve springs and collet. I remember you mentioning over msn that the collets were nowhere to be seen which suggests that it broke or fell off and let the valve fall in. When the collet broke the distance the valve was being forced open from the crusty buildup around the valve was further than the tappets could reach, meaning that when the collet broke the tension of the spring may have shot the valve hard at least partly into the cylinder. Valve then hits the piston and bends the valve and due to the angle and the bend of the valve it moves rapidly with high friction against edge of the valve guide, and combined with the heat from combustion leaking around the ruined valve, melts it. Eventually valve stem snaps or stem seal breaks and allows entire valve to fall inside engine, causing massive damage and causing that spark plug to get completely mashed.

I dunnoh though, just a theory I made up from pictures which in my mind makes sense lol

Either way definitely new head required, and possibly new piston judging by the looks of that cylinder. I'm amazed at how much coolant is sitting in that intake though! Not sure why they are flat top pistons in a second gen though, unless the engine has been rebuilt at some stage (and from the sounds of the overtightened caps - poorly rebuilt at one stage too). Sounds like you have your work cut out with that mess! Good luck man!

btw - I can add things to wiki still - I'm not *completely* hammered for time - I just need information in an easy form where I can add things in without having to do hours of research ;)

old fart
pookie gonna get ya ..:bowrofl: flat streets in your city
and how many traffic lights in the town 2 or is it 3 now

sorry dave .... wiki bit not meant as a negative comment :silenced: :silenced:
btw - I can add things to wiki still - I'm not *completely* hammered for time

seems the timing chain in this TR
has had some kind of tensioner failure

no slack on the chains has bent the timing cog rest

when the tensioner is depressed as per the factory manual reset yet

the chain remained tight could not be fitted to the camshaft

the cam shaft is unusable deep groves -- the caps were torqued to 50 nms

next move check the chains

If this is a TR - it would have that dodgy auto-tensioner setup where it constantly tightens the chain whenever there is movement (and eventually destroys the chain and guides in half the time!). Sounds like that may have been forced out quite significantly if it was able to bend the sprocket bracket =S

I'd just replace the whole lot and keep the tensioner ratchet piece out, so that doesn't happen again. Get a new engine head, get it pressure tested, replace with new roller cams and tappets and see how it goes :D

running fine
no smoke plenty of go in the engine

head and valves lapped fitted new stem seals

one happy magna owner

And Super Buff saves the day once morelol

Over torqued rocker arms will not cause them to jam or stick, the cam may be damaged and also may lock up also but is rare.

Good to see finally someone who does change a head as a unit and not use old cam caps. You can get away with it however is not recommended.

Good to see it is going agiain, may have been a number of things to cause that, once had one go on another car, never found the valve or most of the piston, there were no holes in block or sump either!