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No Compression on 5&6.


hodge

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:( What can cause this. The car is at envy at the min and hes in the process of taking the head off.

Just after a bit of pre warning what to expect. The car is flooding with petrol when its turned over.

A bit of a list of possablities if you dont mind my fellow enthusiasts.

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Dropped a valve likely if zero compression. Exhaust valves usually more common than inlet.

 

Hopefully not a cracked block anyways, that's very uncommon on the 2JZ as is headgasket failure since it's the MLS type as standard. 3S-GTE's in ST205 Celicas on the other hand like to crack the block the moment you start running over 400bhp in anger :(

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Robert at Envy seems to think that the head gasket could be gone, I suppose thats gona be the cheapest option. I cant see the bolck being cracked at all, supra engines are ment to be dullet proof so I heard, but then again it would be just my luck. I had to have 2 engine rebuilds on my Impreza.

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If there's no compression on 2 adjacent cylinders its almost certainly the headgasket blown between them.

 

Surely between them would mean the compression has to go somewhere?

 

Any hydrocarbons in the coolant? - do a sniffer test on the rad.

 

Any water in the oil? - mayo like crap under the oil filler cap is a giveaway.

 

The best diagnosis is a leakdown test though.

 

Cheers,

 

Brian.

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Wouldn't you usually still get some compression with a BHG?

 

My money's on holed piston or dropped valve.

 

But a holed piston or a dropped valve would only give a loss of compression on one cylinder.

 

To get it on 2 cylinders you're talking 2 holed pistons or dropped valves. For them both to occur at the same time, you'd certainly know you'd done some damage ;)

 

Couple that with it being on adjacent cylinders and a BHG between the two is by far your best bet.

 

I've been wrong (occasionally :D) in the past, but I'd be very surprised if I was this time.

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Why?

If there's a leak into the next cylinder, all the charge is going to go that way and out through the appropriate manifold.

 

If you're doing a compression test you crank it over at least 4 times on one turn of the key with the throttle at WOT. This would allow for valves being open depending what part of what stroke they're on..... to repeat I'd still expect some compression if it's just the headgasket.

 

I'd say zero compression on these two cylinders - high EGT's resulting in damaged valves, purely on the face of the information we have. What's the background hodge? How was the car running?

 

Cheers,

 

Brian.

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If you're doing a compression test you crank it over at least 4 times on one turn of the key with the throttle at WOT. This would allow for valves being open depending what part of what stroke they're on..... to repeat I'd still expect some compression if it's just the headgasket.

Brian.

 

OK, I'm not going to continue this "yes it will, no it won't" discussion any more, its all theoretical and I'm not going to argue for the sake of it and risk becoming bad friends over it.

 

Hodge, just let us know what the outcome is when they take the head off.

 

If I'm right, I won't crow, and if I'm wrong, I'll admit it :D

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If there's no compression on 2 adjacent cylinders its almost certainly the headgasket blown between them.

Totally correct.

There may be a cracked head or block but HG is the obvious candidate.

Hey, wouldn't bother me if you're right Geoff - I'd just wanna know why / how - I don't profess to knowing everything and enjoy learning what I've not already learned!

Instead of being compressed, the charge will leak through the HG to the next cylinder which will be on a different stroke.

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:( What can cause this. The car is at envy at the min and hes in the process of taking the head off.

Just after a bit of pre warning what to expect. The car is flooding with petrol when its turned over.

A bit of a list of possablities if you dont mind my fellow enthusiasts.

 

See this thread, I guess you could be looking at something similar. Was the engine modded? Single turbo?

 

http://www.mkivsupra.net/vbb/showthread.php?t=95333

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Standard engine, FMIC, induction kit, boost controller FCD, apart from that there good old Toyota parts.

The car was parked outside of work all night when I stared it it was really spluttery until I gave it a good rev and then it was fine.

It did the same for the next few days butonly when cold.

Then 1 day it just wouldnt start. It turns over but wont fire just floods pots 5 and 6. That about I can tell you folks.

I hope it just is the Head Gasket otherwise im looking at some but money. Its just something else for the wife to moan about.

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I hope it just is the Head Gasket otherwise im looking at some but money. Its just something else for the wife to moan about.

 

Don't sell your but dude, the Supra's a cool car but nothing is worth that :rlol: :rlol: :rlol:

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OK folks HERES THE UPDATE.......................

Been up to Envy today and theyve got the head off.

5 of the valves were stuck open and some of the others were closing to slowly.

Hence why it wont start. Ive been lucky I think, no bent valves nothing cracked or broken.

ive brought the head home and will take it to work net week to strip it down and clean it all up.

While im on im gona do the oil seals and was also thinking of porting it a little.

Any surggestions on any other thinks that need to be done whilst ive got the head off.

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