Hi,

 

The zed has reputedly a problem with the rear cylinders overheating!

 

This is alledgedly down to too much of the water channel flashings left in the block, from the original casting!

They don't let coolant flow to the rear cylinders easily and can be removed if you have an engine rebuild!!

 

Also problems with the plenum design and heat from the turbos can mean the charge air is hotter at the rear cylinders!

 

So just out of interest chuk down what cylinder failed on your motor?

Probs started with 80psi on No 6,(rear passenger side)then progresivly got worse,agree with you about the plenum in that area,think water injection should sort it a fair bit;) Tony

no. 4 for me

Hey Mods - can we have a new option - "Not YET" - otherwise I have to click View Results to see where the weakness appears to be. Much Obliged.

I need to vote 3 times. Is that OK? None of them was #6 as far as I know.

Vote for 6 plus half of 5 - not because the piston went but that's where the gasket went / was on the way out.

1 and 3 are very low.

I have a mate who's engine failed on no.6 because he had uprated turbos and the ignition timing wasn't retarded...

Originally posted by Spezer300zx

I have a mate who's engine failed on no.6 because he had uprated turbos and the ignition timing wasn't retarded...

 

There may be a few more factors than that involved, although it is something to consider!

 

 

It would be interesting to see if they could do this poll in the US and aus and see what conclusions we can come to???

 

Also Dazzer the well known Zed mechanic in Kent says that it is always No 6 that goes on the engines he has to rebuild!

 

It might be interesting to get PeteR's point of view!

Maybe its a Southern thing then and not Z in general.

Originally posted by SRRAE

Maybe its a Southern thing then and not Z in general.

 

UUMmm interesting theory, I think they are dong research into this phenomenom at the University of Southern California:D

but why always 6?

 

Cylinder 5 and 6 are opposite to each other at the back. So why does 6 get it and 5 not?

Originally posted by SRRAE

but why always 6?

 

Cylinder 5 and 6 are opposite to each other at the back. So why does 6 get it and 5 not?

 

Right explanation as follows: The cooler water from the rad enters the block on cylinder 1 and 2 first - and flows to cylinder 5/6 - steadily getting hotter all the time, so cylinder 5/6 is always slightly hotter than no. 1/2. (In theory, 5/6 should get to the same temperature)

 

Not much you can do apart from changing the flow of coolant around the engine. - what you really what is coolant passing sideways through the block, from the inside to the outside, this means all cylinders get even cooling and won't suffer from det.

 

This involves removing the block plugs, etc and is usually found of race cars where engine cooling is of an unmost priority.

 

Easy when you know how hey!

 

(If this all sounds like bollecks then its becuase i've been out on a works-do tonight and am very. pissed :))

 

Regards

Mr S B Willi-hams

xxx

But with that explination cylinder 5 and 6 should be the common failures. Topless is saying more often than not its no6 not 5 and/or 6

Originally posted by SRRAE

But with that explination cylinder 5 and 6 should be the common failures. Topless is saying more often than not its no6 not 5 and/or 6

 

i agree! But cannot explain why its usually 6 not 5!! too stella-ed to give any kind of meaningfull response, so going to abuse other threads then going to bed to be sick on the bird

 

Si.

xx

No 6 failed on me!

UK TT 91

Arthur

Sorry to Hijack but it's still on subject.

 

 

I have heard a lot about compression testing. Where and how much to get this done?

 

 

Cheers :D

Every mechanic should have a compression tester and it shouldnt take more than an hour to do it.

Thanks Stuart. I will ask my local garage.

Not a piston seizure or meltdown on mine...........

 

Big End No. 6 end cap came loose... lol. scrap crank, con-rod, and because piston now had 10mm more throw, it hit the cylinder head and broke lol lol.....

 

ahhhhhhhhh Zeds are great aren't they?

 

 

RCD

By the way true the water does get hotter as it reaches the rear cylinders, but if you saw how much the rear cylinders are blocked by the old casting flashings you would be amazed!

Originally posted by TopLess

By the way true the water does get hotter as it reaches the rear cylinders, but if you saw how much the rear cylinders are blocked by the old casting flashings you would be amazed!

 

But they can't be that bad Mark,I got 12 years out my stock pistons;)

Could it be fuel related.

 

I haven't got a clue here I'm just asking, but how does the fuel rail work ?. Is it constant pressure to all injectors or does it flow in a non loop way if you know what I mean.

 

If it does then maybe there isn't enough fuel in 6 when giving it full shout at say 15- 16 psi on stock injectors.

Macca if you saw the the block I took apart, you wouldn't believe it!

 

Ask AndyG next time you speak to him!

 

The front three cylinders have plenty of flow to them and rears have hardly any!

Stuart,

 

Fuel can be a problem, but the Nissan designers tried to stop the problem of fuel vaporising on the prototype Zeds by increasing the fuel pressure!

 

There is less likelyhood of a consistent design problem in the fuel rail because of it's construction and this has never been highlighted before!

I have solved the problem. No need for any increase in fuel pressure, or need to move up North.

 

I have named the all of the left bank cylinders number 1 and the right cylinder 2.

 

 

I will never have the cylinder 6 or 5 problem then ;)

 

Stuart