L67 Rough Cold Start Issue

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vlad01
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Re: L67 Rough Cold Start Issue

Post by vlad01 »

They did, GM had an aluminium gasket but unfortunately they were never standard equipment here in Aus.
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immortality
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Re: L67 Rough Cold Start Issue

Post by immortality »

Yup. I think GM came out with that fix for the L26/L32 which was the last evolution of the venerable V6 engines.

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Cowtipper
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Re: L67 Rough Cold Start Issue

Post by Cowtipper »

bit of an update

Gave the heads, LIM, and charger case a good degrease in prep to service and some mild porting.

I stripped out the passenger head where the suspect cylinder 3 was and oh my god, all 3 exhaust valves on that head were not sealing on seat correctly. Cylinder 3 exhaust valve stem had 2-3mm of carbon scale built up on it where it passes through the port. 3 hours later its all cleaned up and back together with new stem seals and reground seats.
I have spotted what looks to be a crack between valve on cylinder 5 ... but that cylinder was no where near as dirty as cylinder 3

if i have time tomorrow ill tackle the drivers head
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Gampy
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Re: L67 Rough Cold Start Issue

Post by Gampy »

IMO it is/was a mistake not having them properly crack checked!

But that's just my opinion ...
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vlad01
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Re: L67 Rough Cold Start Issue

Post by vlad01 »

I agree, if there is any signs of cracks I would toss them and get good tested heads. Very common for the ecotec heads to crack due to stuff all material between the valves.
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Cowtipper
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Re: L67 Rough Cold Start Issue

Post by Cowtipper »

Gampy wrote:IMO it is/was a mistake not having them properly crack checked!

But that's just my opinion ...
Thats a fair opinion mate

I would love to find a set of uncracked heads. But the chances of that in NZ are slim and costly.
As I live out of town, walk to work, and have a daily driver for my partner, I'm happy to just experiment with the car in my spare time

Im not chasing huge power.
Previous to my ownership this L67 spent 2 years in a road legal skid pig eating intersections on a Friday night, so to have an issue like i have after a year of my spirited driving on top, I'm happy to take the chance for now and see how it goes
immortality
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Re: L67 Rough Cold Start Issue

Post by immortality »

Indeed. The guy that did my heads asked if I had any other V6 heads that weren't cracked and suggested I hold onto any I come across as they are becoming rare.
Cowtipper
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Re: L67 Rough Cold Start Issue

Post by Cowtipper »

bit of an update here

shes all back together and running well no more issues cold starting etc

HOWEVER i think my wiring to the DFI is failing

the car stalls out randomly driving or idling etc.. a quick wiggle of the dfi wiring (up by the plug) and turn key to restart again

has anyone else come across this issue before?
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Gareth
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Re: L67 Rough Cold Start Issue

Post by Gareth »

Yes, having done decades of road side assist work, the DFI pins loose tension with age. In my experience VT/VX where the worst.
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