GTR Forum banner
1 - 20 of 40 Posts

·
Registered
Joined
·
8,804 Posts
Discussion Starter · #1 ·
I've only had my GTR on the road for two months and it's gone bang again, just a couple hours ago. Got towed to the shop and I'm at work - they spoke very optimistically and said it was just a dead fuel pump, and are currently fitting an uprated Apexi unit for the low low price of USD$550:rolleyes:

I am far more pessimistic and I don't think the car will be running tonight as they promise - here are the details:

was having a run down the highway at a spirited but not WOT 160kph, held that speed for maybe 30 seconds, cruised down to 100kph, then found that the car would not respond to the gas pedal at all. A paranoid look into the rear view mirror, and yep, I'm laying down a huge smokescreen, just like the last time I blew my engine. However, unlike the last time, the engine stops completely. I coast over to the breakdown lane. No smoke, no leaking oil (like the last time I melted a piston). But the engine won't turn over - the starter motor goes and the fan spins, but no sound of anything inside the block moving:eek: I did have a hard thrash with the car putting a Maserati Coupe to shame last night, but the car ran just fine this morning heading to work and not a problem at all this afternoon until it just conked out.

I have a feeling it's piston rings that are gone (my PFC recorded a knock spike of 50) and worse, something has seized up good inside the block. I did take a good look at the oil and although a bit dark, it was still perfectly transparent. It did smell a fair bit like gasoline however, which I'm guessing isn't good.

If the causative factor was the fuel pump dying, wouldn't it have just gone out all at once, or could it have dribbled fuel for a bit, causing the engine to run very lean and then my piston rings go out? But if I had det, surely I would have gotten a knock reading higher than 50 - I've seen up to 117 on it before!

thoughts? or just some prayers might be nice too.....
 

·
Registered
Joined
·
8,804 Posts
Discussion Starter · #4 ·
I don't think so, but well, two test pulls (also not at WOT) at 2 bar could have weakened something in the block, though you'd have never known it as I was racing that stubborn Maserati at 1.3bar last night.

Yes, shamefully, I've been running a stock fuel pump. Didn't think it'd be an issue so long as the fuel pressure stayed up, and also never thought a fuel pump failure could hurt the engine in any way.

If I blew a piston ring or five, what are the odds that only a new set of pistons will have me up and running again? Or is the block fooked for sure?
 

·
R35 Section manager
Joined
·
11,363 Posts
Yes, shamefully, I've been running a stock fuel pump. Didn't think it'd be an issue so long as the fuel pressure stayed up, and also never thought a fuel pump failure could hurt the engine in any way.

Oh dear oh dear. This is a classic example of what cost cutting on mods can cause. Dont mess about with the boost over 1 bar,untill you get things sorted out.
Good luck with it.
 

·
Registered
Joined
·
8,804 Posts
Discussion Starter · #7 ·
I guess one can't really leave even a single piece out - although I'm still having trouble seeing how a blown fuel pump could cause a blown engine. Injectors are 700cc, water and oil pumps are brand new N1s and oil pressure was perfectly steady at 4bar (it has a brand new Z32 oil pressure sender).

Frustrating. But it's true that with the engine that went in, I did not get a look at the internals and how worn they may be.
 

·
Registered
Joined
·
8,804 Posts
Discussion Starter · #9 ·
The stock fuel pump is indeed dead, but replacing it with the Apexi unit didn't fix a thing - the starter motor goes but nothing is moving inside. Seized up. Any speculation to entertain my part-shopping before I get a look at the inside of the block (which won't be for a few days)?
 

·
Registered
Joined
·
8,804 Posts
Discussion Starter · #11 ·
When you turn the key does it make a cherning noise like a cog going round? Its really hard to explain.
yep, something is turning, and battery voltage drops 2 volts just as per usual, but other than the fan spinning, I don't hear anything turning over inside - no chugga-chugga, just whirring. I didn't do it too much - don't want to break it any more than it already is...
 

·
Registered
Joined
·
2,835 Posts
something to do with the solenoid with mine caused it to make a chern noise when I turn the key and the engine wouldnt do anything like you say.

A machanic couldnt understand so I had to get another machanic and I think it was something to do with the solenoid.
 

·
Registered
Joined
·
854 Posts
if theres a spinning or whirring noise when you turn the key, but nothing else then it sounds to me like the starter is spinning but the solonoid isnt engageing it with the flywheel.

hope its that for you anyway...........

have to say though i read the 2bar post and thought to myself 'itll be interesting to see how long that lasts'

good luck mate

kev
 

·
Registered
Joined
·
2,777 Posts
take plugs out, get a small camera in there if no probs then do a compression test, if all is well say 135 ilbs or above per cylinder..take cam cover of to see if belt has snapped.if all is still well then either electrical or fuel..bernie
 

·
Registered
Joined
·
8,804 Posts
Discussion Starter · #18 ·
yeah I'm gonna have a look inside the cylinders, see if the piston rings melted.
My 2 bar test, I don't know if it really caused damage. Both times I touched 1.95bar for a second, maybe less, at 5200rpm. But who knows? Maybe it did shorten the life expectancy of my engine to about two weeks.

If a turbo wheel went, and sent shards into my engine, wouldn't I have heard something?

I'd be surprised if the cambelt snapped - it's a Tomei with 3000km on it from new, and the tensioner and idler are just as new.

Other than lots of smoke pouring out the tailpipe and the engine going out, no sounds, no pops, no bangs, no nothing. No oil leaks, and oil temps were normal. Water temp though, when I pulled over with the non-running engine, rose (I had the ignition on) to 85 degrees before cooling off. Oil was at 80 degrees and cooled off normally.

So something may very well have gotten very hot, and my fuel pump is confirmed dead. I wonder why it would take the starter solenoid with it, although we'll give that a check of course.

If the bottom end is indeed knackered, all I'm hoping for is that the cylinder walls and crankshaft are ok, because instead of buying a short block I'd prefer to rebuild with new pistons, bearings, and conrods, so I know for sure what's inside my engine.
 

·
Registered
Joined
·
8,804 Posts
Discussion Starter · #19 ·
car failed compression on all six cylinders. defo the piston rings. everything else checks out ok. so here's my hypothesis:

- cruising on the motorway, fuel pump fails. I don't notice because I'm cruising down from 160kph to 120kph

- during the pump failure, either the pump still had a small degree of output, or as the fuel system depressurized, gas was still going into the engine, causing it to lean out significantly.

- in the span of about 10-20 seconds, from where I let off the throttle after reaching 160kph, and coasting down to 120kph, things got very hot inside the engine, melting all six piston rings. I could not monitor this because I do not have either an EGT nor a fuel pressure gauge. As a bitter irony, a full complement of Apexi gauges plus an NTK wideband lambda is enroute to me from Nengun and the US (ordered a couple weeks ago).


Well, if life gives you lemons, make lemonade. I didn't really trust the replacement engine I was given (for free, so it could not have been a particularly good one), so I'll take this opportunity to do the following:

- piston rings, obviously
- uprated conrod bolts
- new bearing shells all round
- possibly new pistons

I'll get confirmation tomorrow, but I have a feeling that the block is ok - I had full oil pressure all the way through this whole breakdown, 4 bars worth. I'd rather not bore out to 87mm.

I got a fixed quote of the equiv of about 900 GBP for labor costs of the engine teardown and rebuild. How does this compare with UK prices?
 

·
Registered
Joined
·
341 Posts
er am i being stupid or domething but if the engine wont turn over off the key, how did you manage to do a compression test?

have you tried takin the plugs out and turning the engine over by hand to see if it actually is siezed. as somebody mentioned mabe the starter aint engaging or the flywheel is stripped
 
1 - 20 of 40 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top