Rattly G200Z

geminilover3236 · Post by **geminilover3236** » Tue Dec 18, 2012 2:28 pm

This is a quick video of my G200Z, It's a high compression engine 10:1, electronic ignition, 4-2-1 extractors, ported head, sidedraft dellorto 40 carbie.

http://youtu.be/Wd6Wf7j8w4E

It's a bit hard to tell in the video but it sounds overly rattly compared to other G-series I've had. Anyone got any ideas why and/or if it's an issue that I should be concerned about?

Cheers.

tobytj · Post by **tobytj** » Tue Dec 18, 2012 5:11 pm

Try cam chain adjuster slide bent in the shape of a banana and all the teeth smoothed off the adjuster. Thats what happened to mine.

Although G200 adjusters are supposed to be prety good I had one that had the pawl and adjustment teeth rounded off so it would not lock. The chai actually broke the adjustment slider in half and chewed through the base of the guide on the fixed side and into the block.

Do not ignore the rattle or the chain will jump and bend valves or the chain will chew through the water jacket in the timing cover. Good chain and tensioner and lifters adjusted the G200Z is meant to be a pretty silent engine.

Easy to check.

Wrx884 · Post by **Wrx884** » Tue Dec 18, 2012 7:23 pm

tobytj wrote:Try cam chain adjuster slide bent in the shape of a banana and all the teeth smoothed off the adjuster. Thats what happened to mine.

Although G200 adjusters are supposed to be prety good I had one that had the pawl and adjustment teeth rounded off so it would not lock. The chai actually broke the adjustment slider in half and chewed through the base of the guide on the fixed side and into the block.

Do not ignore the rattle or the chain will jump and bend valves or the chain will chew through the water jacket in the timing cover. Good chain and tensioner and lifters adjusted the G200Z is meant to be a pretty silent engine.

Easy to check.

does this apply 2 the 1.6 also? noticed our other gem is a bit more rattlely than wat ive heard b4 also.

geminilover3236 · Post by **geminilover3236** » Wed Dec 19, 2012 10:38 am

Thanks Toby,

I ran out and popped the rocker off and checked it and it was all fine. The chain was sitting centred, the tensioner all the way out and when you rotate the engine normal rotation it would stay tensioned, when you tried to rotate it the other way it would try to de-tension but is stopped by the teeth on the tensioner. There was still some movement though and the chain isn't REALLY tight but it isn't loose enough to jump a tooth.

Hope that makes sense.

It is a 1.6 head, if they are smaller (vertically) then this could be why there is some slight slack in the chain. Also the tensioner material that the chain rubs against could be worn down so isn't holding it out as much. The tensioner literally cannot go any further out though.

LOK15 · Post by **LOK15** » Wed Dec 19, 2012 12:03 pm

it does indeed sound like timing chain rattle , but im on a laptop with crap speakers. Could be excessive piston slap. We need a bit more history of the motor.. has it gradually made this niose , did it do this from the time you put it in and started it? , since doing a mod to the motor?

geminilover3236 · Post by **geminilover3236** » Wed Dec 19, 2012 10:11 pm

Motor is genes old g200z. unknown K's on it.
I since put the 1600 head on it. it gets a flogging. its in a drift car. Got pretty hot last time I was out on track. (boiling over hot)

Gradually started making this noise. Wasn't as bad when I first got it. Still a rattle though.

77tc_coupe · Post by **77tc_coupe** » Wed Dec 19, 2012 11:06 pm

Grab a peice of timber place it to your ear and then Place it on different areas of the engine and the timer will act as a stethoscope, you may be able to pin point where this noise is coming from using this method, therefore making it easier to find out what is wrong.

tobytj · Post by **tobytj** » Thu Dec 20, 2012 8:22 am

The four key suspects here are tappets, timing chain, big end bearings, pistons. From your description of drifting and flogging big end bearings are shortening to second favorite.

Each problem has a specific noise signature.

Tappets - you can check and eliminate and the noise signature is intermittent tapping that does not vary with engine load just revs.

Chain - continuous steady rattle and still my odds on favorite to win

Big ends - rev the engine steadily and then back off. A big end rattle will be loudest as you back off.

Piston Slap - will be louder under load.

As said it sounds like a chain. if the adjuster is out all the way that puts lots of stress on the pivotted guide and and they bend - that's what happened to mine.

LOK15 · Post by **LOK15** » Thu Dec 20, 2012 8:33 am

do you have an oil pressure gauge on it , this will help tell if its big ends or not.

TURGEM · Post by **TURGEM** » Thu Dec 20, 2012 10:25 am

77tc_coupe wrote:Grab a peice of timber place it to your ear and then Place it on different areas of the engine and the timer will act as a stethoscope, you may be able to pin point where this noise is coming from using this method, therefore making it easier to find out what is wrong.

This is good idea, can be a big arse screwdriver (fits in ear well)...

geminilover3236 · Post by **geminilover3236** » Fri Dec 21, 2012 10:09 am

From toby's analysis, timing chain seems most likely.

Just had a full day on the track yesteday and it performed great and had no issues at all. still plenty of power.

Oil, pressure and temp gauges are next on the list. Then we can know a little more about what's going on down there.

Geminis4ever · Post by **Geminis4ever** » Fri Dec 21, 2012 10:28 am

Ive got the same prob with mine and have asked mechanic what it is
(As drives me f*#cking crazy) and he said one of two things either noisy
tapetts or if when bigger cam was installed maybe wrong or standard
springs installed? Yet to get proper diagnosis but sounds like a ticking
time bomb ATM

geminilover3236 · Post by **geminilover3236** » Thu Jan 03, 2013 9:18 pm

So I was thinking, seen as it's a G200Z with a 1600 head. doesnt that make the total height of the engine smaller than a standard G200Z. So the length from top cog to bottom cog for the timing chain would be shorter yes?

Would it be possible to fit a chain minus 1 link and would this fix it, i.e. making the chain tighter as the tensioner is fully out atm and cant physically go any further.

RedGemCoupe · Post by **RedGemCoupe** » Fri Jan 04, 2013 7:53 am

As Lok said it is a bit hard to tell over a computer. I had a G180 that was a bit rattly and everything looked fine. It still ran and performed great.

Turned out to be a cracked piston skirt.
The skirt hadn't broken completely but it was still enough to make a rattly noise. Even with the head off it was not obvious.

geminilover3236 · Post by **geminilover3236** » Fri Jan 04, 2013 11:15 am

Wow, now that's not something you would expect haha.
Yer pretty much same boat here. runs fine, great power, just a little noisy. Im about to embark on a 8000km roadtrip to the other side of the country so I want to get my bases covered. Will probably just replace the chain.