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The mkiv Supra Owners Club

No Compression on 5&6.


hodge

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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...

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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.

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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

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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.

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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.

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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.

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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.

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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 ;)

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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

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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!

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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.

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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 ;)

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