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Discussion Starter #1
Hey guys,
Just took my car into the gas mechanic for a tune. He has told me that the car now runs nice on gas but is a bit lumpy on idle.
He has advised that the tappets are too tight and need doing.

I'm not up to speed with this, even though I'm mechanically minded and advised it was 1800 bucks to do the whole job.

Is this reasonable

Its an 02 GU 4.8 on injected gas.

Cheers

Sam.
 

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You surely could not have heard right...$1800 ???

I do my own but was once quoted $100, I would estimate up to $150 a fair price interesting to see what others think.
 

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Discussion Starter #3
oh yes, i definitely heard right.

Thank you for the reassurance. am picking up the car tomorrow without this service.

Cheers
 

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an hour and a half all up is all it should take, bit less for some.
 

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nissan
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You surely could not have heard right...$1800 ???

I do my own but was once quoted $100, I would estimate up to $150 a fair price interesting to see what others think.
Do 4.8s have rocker arms? If they don't I understand the price quoted. Anything that has rocker arms with adjusters on the end is a piece of cake and shouldn't be much more than a couple of hundred bucks even allowing for a new rocker cover gasket.

I once stupidly offered to help a friend do the tappets on a 5 cylider VW diesel engine and I would want every bit of $1800 to do it again. Adjustment was by replacing shims in the tappets which could only be accessed by removing the overhead cams which could only be removed by taking off the front timing cover. This required removal of a bunch of stuff including the harmonic balancer which required removal of the radiator to provide access for the puller. The job went on and on and on and took pretty much all weekend for the two of us. The cramped engine bay of a VW Transporter did nothing to help matters and we wasted heaps of time trying to do stuff without removing too much other gear. In the end there was little left in the engine bay by the time got access to the tappets.

If a 4.8 is anything like that VW I can see why it is $1800. Otherwise its a sting.

Cheers,
 

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Not 100 % sure, but i think the 4.8s use shims to adjust clearance, not as simple as the 4.5
 

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Adjusting valves where shims are employed.

I'd be checking a maintenance manual .... if they are like the ZD30 the shims can be removed measured and replaced without removal of shafts etc.
 

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nissan
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Hey guys,
Just took my car into the gas mechanic for a tune. He has told me that the car now runs nice on gas but is a bit lumpy on idle.
He has advised that the tappets are too tight and need doing.

I'm not up to speed with this, even though I'm mechanically minded and advised it was 1800 bucks to do the whole job.

Is this reasonable

Its an 02 GU 4.8 on injected gas.

Cheers

Sam.
Sorry but before I say I am suss, let me get this right. He says it now runs fine on gas and petrol but idles rough. Or runs fine now on gas but idles rough and didn't mention petrol. What combination was he referring to?

Also out of curiosity has anyone here had to increase their tappet clearance. I have only had to increase it after head mods or replacement of parts which has removed the aging wear factor.
 

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To do the shims on a 4.8 head takes a full day by the time it is all said and done, plus the cost of shims is required, so I reckon around $1000+ would be the ballpark you will be looking at. Maybe a little more if the LPG stuff has to be moved out of the way etc. It's a crap job.

If the car is on gas the valve seats will recede over time, eventually causing the valves to not fully close on their seats. This will cause an injected gas engine to idle rough on both gas and petrol, whereas a mixer gas engine will idle fine on gas but rough on petrol.
 

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Discussion Starter #11
Thanks for the detailed reply guys.

I ended up picking up the car without having the tappets done.

I'll try and be more clear. The car runs fine on Fuel. The idle is pretty smooth, not rough at all. car runs excellent on fuel.

On LPG, the car drives great, on idle when its warm, its a little rough, and when I say rough, i mean the idle is constant, but i can feel it idling. I cant feel the car idle on fuel.

He's tuned and fixed up the gas system (it wasn't auto switching over and the last guy that touched it deleted the tune and couldn't re-tune it) so im happy with that.

i'll have to call around to find someone that can look at the tappets.
I do everything myself, but I don't have enough confidence to do it, so id rather take it to someone who knows.
 

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Check that your fuel injector seals aren't leaking, it could cause the symptoms you described.
But then again its probably going to come down to a good tune.

Mixer or Injected LPG ?
 

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Discussion Starter #14
Took the car to a place in Mt Waverly which was highly recommended by patrol owners having their 4.8's re shimmed there.

Glenmount AutomotiveDirections
Address: 113/115 Ricketts Rd, Mt Waverley VIC 3149
Phone:(03) 9544 4000

All up cost about 800 to do, took 2 days.
Very happy with their service.
 

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Did you find out if the tappets were too tight.................
 

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Discussion Starter #16
Did you find out if the tappets were too tight.................

Yeah, We found that the intake valves were too loose, and the exhaust valves were too tight and we had to replace about 20 shims all up.
The shims were non genuine, so they were replaced at one point. The prev owner did tell me he did the head on it at some point.

All in all pretty happy. and peace of mind for not too much mulah.
 

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nissan
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.. the exhaust valves were too tight ..
Pretty normal for an LPG engine with some Ks on it.

I'd say $800 is a good price and still within cooee of Scotmeisters $1000 estimate. The $1800 was obviously a rip though.

Cheers,
 

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Discussion Starter #18
Pretty normal for an LPG engine with some Ks on it.

I'd say $800 is a good price and still within cooee of Scotmeisters $1000 estimate. The $1800 was obviously a rip though.

Cheers,

Yeah the 1800 was def. a royal rip.

Quite happy. I've seen what is involved and its def worth every penny of 800.
 

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Yeah the 1800 was def. a royal rip.

Quite happy. I've seen what is involved and its def worth every penny of 800.
Yeah, I've never seen under the rocker cover of a 4.8 but when someone said they've been quoted a hundred bucks for valve adjustments I knew that all engines were not equal in that department.

Good you got to it when you did. If you leave it too long you can burn exhaust valves and the head has to be redone.

Cheers,
 
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