Hi guys,

 

As you all know by now I've been having some problems with my engine making funny rattling noises. I can best describe the noise as the noise the engine produces in a manual trans car when you're trying to pull away in too high a gear - i.e., your valves start fluttering. The thing is that my engine (A/T) only produces this noise when it has been thoroughly warmed up and only in the top two gears (i.e., 4th and O/D)when accellerating lightly.

 

I was just sitting here thinking (as you do) and thought that perhaps my hydrolic lifters are causing this noise. My problem is that I know nothing about them and would really appreciate someone giving me the lowdown on them.

The reason I'm thinking it *could* possibly be the lifters is because my partner's car's tappets flutter when the engine is warm, producing a very similar noise. But since our Zeds don't have tappets it could either be the lifters or the actual valves.

 

Any and all thoughts are most appreciated and please tell me if I'm completely on the wrong track here.

 

Cheers fella's,

 

Danny

Danny

What you describe as valve fluttering is almost certainly pinking or pre-ignition or detonation. Try using superplus fuel and see if it goes away.

It cant be the hydraulic tappets cos thy're pressurised as soon as engine starts and dont loose pressure just because you accelerate gently in 3rd or 4th.

Is your with a JWT chip or other? Maybe your timing has been set too far advanced.

Or else something else is rattling. Or maybe overheating. For instance if your water level is too low you could have air pockets in the cylinder heads and that can cause very hot regions in the combustion chambers that then leads to pinking. Never hear of it in a Z but just a thought.

Willie

Also weak mix thru air leak in manifolds pipes etc cud cos pinking!

 

Do you get full boost on WOT? If boost is down you cud be losing thru same air leak. I found one of my boost pipes slack once.

Thanks for your reply Willy. In response the following info:

 

I have recently changed from a stock Nissan chip to a JWT chip and this particular problem remained unchanged. Note: haven't installed boostjets yet so I'm not running any higher boost than standard.

 

The car is running full boost on WOT.

 

Have checked and reset the timing to recommended 15 degrees BTDC recently (timing was previously retarded to 17 degrees by AndyP in an attempt to sus out this problem).

 

I have had cooling system problems over the past 6 months (starting with a blown waterpump) and have had the rad re-cored and replaced the two reservoir tanks on either side of the rad core. Car is currently not overheating, nor is it loosing excessive amounts of coolant - just a minimal amount which I put down to fluid being passed to the expansion tank (which is full) on long runs.

 

I've just last weekend had the car up on a ramp and checked the underside of the car for loose heat shields, nuts, bolts, pannels, parts, etc. All seems tightly put together

 

Have recently installed JWT pop charger and checked *most* hoses for leaks - seemingly all is okay.

 

Further more, I have no visible (or smellable) fuel leaks but am thinking of replacing the fuel pressure regulator and damper in the near future.

 

So, it looks like I'm back to square one

 

Any more thoughts guys?

 

Danny

 

PS - Although I have taken great care not to ever let the engine overheat, I can not speak for the previous owner. Could it be that if he did let it overheat that valves have been bent or something like that?

 

Danny, you need to come over to Holland soon mate !

 

can't wait to test out the ConZult-software to see if we can somehow diagnose/troubleshoot your problem.

 

did they replace the thermostat once they did the pump ? (they should have..)

 

Did you ever check the injectors ?

You can do this manually by unplugging the coils one at the time and see if the revs (at idle) drop slightly.

The detting could be caused by a dodgy injector. (I currently have this problem with my TT)

 

-Eric

 

 

[This message has been edited by lymon (edited 25-01-2002).]

Danny

Any chance theres a bit of carbon inside? Maybe the previous owner did lots of city driving - mabe needs some fast motorway work to burn out the deposits!

BTW going to 17 degrees would be advancing and likely to lead to pinking - maybe it needs to go to 12 or so. Just thinking if it was pinking it should go to safety boost as well so maybe your rattle is from something else.

Willie

Eric mate! Long time no hear fella - how's it going? I know I should come over to Holland ASAP but as the money situation still hasn't resolved itself there is not much of a chance for me to come over - perhaps late Feb or early March. Definitely interested in getting together with you to test your ConZult software. As for the dodgy injector, I'll give it a go if/when it finally stops pissing down with rain over here. My Zed currently sports a full size swimmingpool in the driverside footwell - courtesy of dodgy T-bar/window seals. Nissan did replace the thermostat (twice) when they did the H2O pump. Speak to you soon mate!

 

Willy - I'n not sure about the state of my engine's innerds but until recently I used the car on a near daily commute between Birmingham and London, so I think that if there was a carbon build-up it would have been burnt off my now. You're right about going into safety boost when pinking and I'm fairly convinced it doesn't as I can shove the boost needle nearly all the way to +7 (have Jap boost guage) even when the rattle occurs.

 

Still stumped and

 

Thanks for your input guys,

 

Danny