View Full Version : No Compression on 5&6.
:( 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.
if theres no compression this is headgasket failure or cracked block, perhaps a bent valve or somthing?
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 :(
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.
Well, they don't have to take the head off to further diagnose - they could do a leakdown test.
Cheers,
Brian.
geoffvalenti
09-01-07, 17:39
If there's no compression on 2 adjacent cylinders its almost certainly the headgasket blown between them.
geoffvalenti
09-01-07, 17:41
Well, they don't have to take the head off to further diagnose - they could do a leakdown test
Brian.
No point really, its going to be the headgasket. They may as well use their time constructively rather than trying to diagnose the obvious ;)
Wouldn't you usually still get some compression with a BHG?
My money's on holed piston or dropped valve.
Hope I'm wrong though. Good luck Hodgster
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.
No point really, its going to be the headgasket. They may as well use their time constructively rather than trying to diagnose the obvious ;)
Totally disagree - I agree with Jake I'd expect at least some compression.
If there's no compression on 2 adjacent cylinders its almost certainly the headgasket blown between them.
:yeahthat:
geoffvalenti
09-01-07, 18:03
Surely between them would mean the compression has to go somewhere?
Brian.
Yeah, well it does, through the hole in the gasket, into the adjacent cylinder, and out the exhaust or inlet manifold depending on what stroke the adjacent cylinder is on.
geoffvalenti
09-01-07, 18:09
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.
geoffvalenti
09-01-07, 18:11
Totally disagree - I agree with Jake I'd expect at least some compression.
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.
Andy Supra
09-01-07, 18:16
Hodge i'm not clue'd up but hopefully seeing as Xmas just went it won't be to expensive.
All I can say is it's the most ideal time of year for the news though least weather is crap so your not missing much driving it out and about.
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.
geoffvalenti
09-01-07, 18:44
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
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!
Cheers,
Brian.
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.
Chris Wilson
09-01-07, 23:14
:( 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
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.
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:
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.
Check the valves very carefully...
Personally if it was me and you were going to rebuild the head from scratch, I would replace the valves and grind them in.
Chris Wilson
11-01-07, 18:47
In nearly 40 years of building engines I have only ever once seen an engine with a valve stuck open that wasn't bent or the engine was in the most terminal meltdown. Only one was stuck, and it was on a Ford that had known problems with this. For so many to have stuck open in an engine in regular use astounds and amazes me. There MUST be more to it than that...
Please dont say that Chris, Im hoping it will do the job.
My opinion ludicrous as it is. This has happened twice to me but not so severe last time. I think its all to do with petrol sound stupid I know but this is my story.
The retard i bought the car off used to run it on 95 ron unleaded, (bloody idiot). Since ive owned it ive always used super unleaded 98 ron.
I tried some BP ultimate 1 day parked the car up over night and when I started it the next day it was banging and pluttering, wouldnt tick over, I had to keep my foot on the throttle just to keep it going. I was seriously overfueling to the point of the ehaust was stinking of petrol and if i reved it it blew out black smoke, I filled up the car with super and after a while it was fine.
This time, my local garage was closed so I again put some BT ultimate in from the same garage, and again I parked it up over night and had the same symptoms, bu if i reved it it would clear and be fine, Just struggled starting when cold again, then it just wouldnt dtart at all.
However far fetched it sounds I think its been accessive carbon build up due to overfueling thats caked up on and round the valve.
this is my story and im sticking to it, well hoping its right anyway.
There MUST be more to it than that...
Plus the fact if you had 5 valves stuck open you would have at least 3 cylinders with no compression :)
geoffvalenti
11-01-07, 20:07
I'm amazed.
Obviously I agree with CW on this (I wouldn't dare argue :D) in that, in all my years of working on cars, I've never come a cross a car that managed to get one valve stuck open by being left overnight, let alone 5 :shock:
As for the cause of it being down to using BP Ultimate, that's pushing the boundaries of believability far beyond wishful thinking, and deep into full fantasy mode :taped:
A build up of carbon on the back of (inlet) valves enough to hold them open, takes thousands of miles (if it even occurs these days, with better fuel additives) certainly not the odd dodgy tank of fuel, no matter where it came from.
I'd certainly be looking very carefully at everything before I even considered going to the expense of having the head refitted
Chris Wilson
11-01-07, 21:00
I'd have all the valves out, all the stems looked at, all the buckets looked at, and all the guides looked at. It won't be the type of fuel, but maybe if it was so seriously overfuelling the actual engine oil may have become saturated in petrol and like water, it wouldn't then lubricate things properly, but if that was the case I'd have expected the turbos to have gone long before the valves seized up. If you don't fully strip the head it will come back to bite you, almost guaranteed. You must sort the overfuelling out, too. O2 sensor and any cats will probably be dead, too.
Cheers guys, your making me feel a whole lot better.
Anyway, fingers crossed when I finished the head the cars gona fire up.
Come on guys give me some positive vibes here please.
Cheers guys, your making me feel a whole lot better.
Anyway, fingers crossed when I finished the head the cars gona fire up.
Come on guys give me some positive vibes here please.
Mate all will be fine, I am going through it just now too with my car bent rear subframe and there is going to be light at the end of the tunnel.
I hope it all works the way you want it to, but of it doesn't it would be worth finding out what a replacement head would cost - you might be surprised (pleasently).
Tricky-Ricky
11-01-07, 21:11
At a rough guess going along Chris thoughts of petrol contamination, problems with the follower buckets seizing, or possibly if the former owner was a muppet, i wonder if the head gasket had gone badly and neglected, and in the resulting overheat something has distorted or even the valve springs have lost some of there tension.
I dont think it was contminated fuel i think the car just didnt like it. You wouldnt believe the amount of black smoke it was chucking out when I reved it and the smell of petrol was horendous, I could get high if I stayed next to the exhaust for a min or 2.
geoffvalenti
11-01-07, 21:32
Cheers guys, your making me feel a whole lot better.
Anyway, fingers crossed when I finished the head the cars gona fire up.
Come on guys give me some positive vibes here please.
Go and see CW, don't ask his advice about cars, just watch how his ostriches bury their heads in the sand, and see if you can perfect the technique ;)
Chris Wilson
11-01-07, 21:48
Positive Vibes: Nail the head back on with the old gasket, spray it with WD40, all will be dandy :)
Reality Vibes: Strip it, fix it, find the overfuelling fault, fix it, check for other damage, fix that :)
Do I use 4 or 6 inch nails.
Positive Vibes: Nail the head back on with the old gasket, spray it with WD40, all will be dandy :)
Reality Vibes: Strip it, fix it, find the overfuelling fault, fix it, check for other damage, fix that :)
:rlol:
geoffvalenti
11-01-07, 21:59
5 inch are usually best in these circumstances ;)
Chris Wilson
11-01-07, 22:06
Do I use 4 or 6 inch nails.
Annular ring 6 inch, in chrome moly plasticene, of course :)
Do I use 4 or 6 inch nails.
:rlol:
In all seriousness the only engine I know of that had a valve stuck open had been sat for two years. And that was only one valve. You can hope for the best but you must also plan for the worst. A good used head with full valvetrain may be the way to go.
-Ian
Supragal's had a stuck valve or two I think.
In all seriousness the only engine I know of that had a valve stuck open had been sat for two years. And that was only one valve.
-Ian
Supragal's had a stuck valve or two I think.
That's the one :)
-Ian
Was the BP ultimate that caused this spluttering from the same petrol station?? Just wondering if its water in the fuel causing valve stem corrosion (unless they're stainless?).
Otherwise cylinders 5 & 6 are likely to be the hottest running. A crap oil used by the previous owner could have led to varnish deposits being burned onto the valve stems, reducing clearances and gumming up the valve causing it to stick?? Or possibly react with the fuel (inlet valves only) if there's some specific additive in the fuel that turns the varnish into a glue like substance??
All just guesses though!
Yeah it was exactly the same petrol station.
The oil in the car was bought from Envy.
Its just the inlet valves I thing that wre clogged up ive only got 1 out at the min and ts thick with carbon deposit, no way would that of gon back into its seat.
Go and see CW, don't ask his advice about cars, just watch how his ostriches bury their heads in the sand, and see if you can perfect the technique ;)
They're emus. I don't *think* they bury their heads?
geoffvalenti
13-01-07, 15:02
They're emus. I don't *think* they bury their heads?
There's always one smartarse in every thread :D
Anyway, I'm still trying to work out how these valves coked up overnight after 2 tanks of BP Ultimate.
Even if you'd have stuffed coal down the inlet manifold I doubt if it would have had the desired effect ;)
Soonto"HAS"soop
13-01-07, 17:02
Clogged oil pathways?
Mind, I suppose Envy would of figured that.
Well when ive finished the head it will be like a spanking new one, everything clean and shiney. So when its all bolted back together it should be ok.
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