L67 Rough Cold Start Issue

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Cowtipper
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@001 VU l67 manual Ute

L67 Rough Cold Start Issue

Post by Cowtipper »

Hey Team!,

This story is over the last couple of months, it gonna be long but i wanted to put every detail i can here..

Car Specs:
2003 VY Spac
Getrag Manual
L67 V6 (Supercharged V6) (150xxxks)

Motor related mods:
Alloy LIM Gaskets
VY L67 Loom and computer (reprogrammed to suit manual)
Xforce stainless headers, Cat deletes, VY R8 Catback system
87mm Pulley

During the end of a 30min drive, i noticed what sounded like rattling tin cans when i planted my foot in 5th gear at 100kph (i could hear it knocking when load is applied).
At this point my water gauge was reading normal (just under half), but my oil pressure gauge was very low around 18 to 22is psi even at 100kph/1800rpm/5th.

i had to pull over on roadside to make a phone call anyway so i figured ill check under the hood aswell.
Noticing i hadn't pulled off the road far enough, i put it in 1st gear and slowly tried to move . This is when the car died/stalled.
However when trying to start the car again, it was cranking as if the battery was near dead. It was still turning over, just really slowly.

Seeing abit of steam coming up the hood, i popped the bonnet to find the majority of it rising from around the exhaust headers on block and that's when i realized my idiot mistake,
I didn't screw down the damn radiator cap after checking it before leaving home so its boiled out all the water! :rant: :rant: :rant:

After 45mins or so of waiting for the motor to cool down, i had a mate bring me water which filled the motor. Turn key and car fired on the first crank and now idling away happy as again!

Since that day, on a cold start the car would splutter and miss for a short period before it comes right again. As time has gone on i still drive it on the odd occasion when needed (if the missus has her car) but the car has been slowly getting worse with cold starts. It got to the point where it takes nearly a minute to clear up even with some throttle.

Now to be clear, after the miss goes away, the car runs as it should with no overheating issues and a constant 30-40ish psi oil pressure at idle warm or cold ramping to 60psi under load.
I knew off the bat the overheating event would cause some issues, So I ordered all the gaskets etc to get ready to repair her

In the meantime, works busy and time is short so i make sure to check over the car prior to driving everytime.
While checking the radiator I notice 2 things consistantly:
1. Regardless of how much driving on any trip, i loose around 2 to 5 cups of water each time which i top up.
2. Prior to a cold start there is full pressure in the water system and it seems like it stays that way indefinitely while cold (even after 2 or 3 days it has huge pressure in the system), I have a locking radiator cap so i let the pressure out every time before starting (mostly air)
I also checked the plugs and cylinder 3 had what looked like corrosion on the plug (could be detination) which at this point i already knew it must be headgasket failure. Since then it was parked up till i finally had the time to start the repairs.

Findings when stripping the L67 down:
1.LIM bolts were tight and the Alloy LIM gaskets are intact with no damage on seals or marks to prove water has pushed past them.
2.The head gaskets, they are mint, i mean absolutely faultless, with no breaks/fractures in them and no water marks on the block or heads to indicate water has been pushed around.
3. In cylinder 3, the exhaust valve has similar corrosion (white speckles caked on) as the spark plug.

Valves are coming out to grind the seats
I know cracked heads are a common issue on these motors, but if its not obvious to my naked eye i dont believe its would cause this big of problem.

Anyways thanks in advance for your replies, and thank you for taking the time to read my tale.
immortality
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Re: L67 Rough Cold Start Issue

Post by immortality »

Take the heads and have them crack tested.

I recently had a set of ecotec heads machined, I spent ages cleaning and washing em and could find no cracks at all visually however once the shop had put the heads in acid and started cutting new seats some minor cracks did appear. The machinist was certain not enough to be off issue but they can be hard to see. Over pressurized cooling system indicates combustion gasses are getting in there somewhere, you can get test trips which lets you test for combustion gasses in the cooling system (although a mute point as the offending coolant will be drained and long gone no doubt).
Charlescrown
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Re: L67 Rough Cold Start Issue

Post by Charlescrown »

What test strips can test for a blown head gasket? I use them for coolant concentration and PH level.
immortality
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Re: L67 Rough Cold Start Issue

Post by immortality »

It's a little test kit, not strips (my bad).
'quipt4it
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Re: L67 Rough Cold Start Issue

Post by 'quipt4it »

I have a similarly long story but I'll cut to the chase lol
Although my case is a different application, I too had what seemed to be water getting into a cylinder. Damp plug etc. Also, the overflow recovery did not work as it should. It would not draw back all the coolant under vacuum relief (as when cold).
Rather than look for additional work, I thought I would just re-torque the head bolts on that side of the engine.
That did the job. No more leaks, coolant recovery working as it should.

In your case, it is likely (if it isn't a crack), that the excessive heat cycle, (remember everything expanded then relaxed significantly), that the head bolts lost the required clamping force on the head gaskets. We are not looking for gushing geysers here, but steam that is being forced into a cylinder under pressure.
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vlad01
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Re: L67 Rough Cold Start Issue

Post by vlad01 »

I have a similar issue in my daily shitbox VP but it only started a few months ago randomly. It runs really rough on cold start and heaps of steam comes out the exhaust when it does that, smoke (steam) screens out the whole road when I leave for work in the morning.

I figure it's just the valley gaskets as they haven't been changed in 130k and there is no pressurization of the cooling system beyond what is normal. But I'm not going to worry about it as I just bought a new VP recently to replace this clapped out shitbox.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
Charlescrown
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Re: L67 Rough Cold Start Issue

Post by Charlescrown »

Vlad whats the problem with the valley gaskets? I have seen it before where the owner was getting oil in the radiator and was surprised when they fixed it by changing the valley gaskets.
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vlad01
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Re: L67 Rough Cold Start Issue

Post by vlad01 »

The plastic that supports the o-rings degrades over time and they collapse so the o-rings get sucked in allowing coolant/oil to flow from port to port and mix. I have seen where the coolant travels along the o-ring groove and leaks into the intake port and floods the engine with coolant.

I had to scrap 2 engines before becasue they sat around and completely filled with water and rusted out the bores and seized.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
immortality
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Re: L67 Rough Cold Start Issue

Post by immortality »

Charlescrown wrote:Vlad whats the problem with the valley gaskets? I have seen it before where the owner was getting oil in the radiator and was surprised when they fixed it by changing the valley gaskets.

This...
Image

You can see where the gasket has collapsed around the coolant port on the Captains side, you can also see the same on the side of the intake ports on the same head on either side of the coolant port. Sure fire way for coolant to find it's way into the combustion chamber.
Charlescrown
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Re: L67 Rough Cold Start Issue

Post by Charlescrown »

With the age of the engine I would have thought they could have fixed that one.
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