4.2L (Cold) Rough Start/Cam Shaft Variators

Wanderer

Member
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5,791
Is it the same fundamental issue for the dry sumps as we'll as the wet sumps? Someone on ML rigged some oil feed to his and cured it (dry sump) but he never fully shared the howto.

My dry sump does it sometimes when cold, and never while warm/hot. Has done for the three years I've had the car.
 

Oishi

Member
Messages
825
not sure that is the full explanation DG was expecting ;)
No, I think "Bugger" sums it up nicely.;)
Wanderer, we got into a discussion on ML about drysump cars and variators. There is an oil accumulator that feeds the top end, and keeps constant pressure on the variators. I have observed that with the key turned to position 3, ign. on but not start, that my oil pressure will rise without the engine running. I postulated that the solenoid valve was open and allowing oil from the accumulator to backfeed the system. I was told I was wrong. However, I have further observed that the higher the oil pressure is on shutdown, the higher the pressure observed on the next start. The theory was that a failing accumulator would have the same symptoms as failing variators. I tend to agree with this. Hope this helps..Ed
 

philw696

Member
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25,123
They certainly need do as the noise is the effect of the wear going on with no oil feed there.
I know there are a few on here that like to go in hard and dry but it's usually painful for someone.
 

Gp79

Member
Messages
1,393
No, I think "Bugger" sums it up nicely.;)
Wanderer, we got into a discussion on ML about drysump cars and variators. There is an oil accumulator that feeds the top end, and keeps constant pressure on the variators. I have observed that with the key turned to position 3, ign. on but not start, that my oil pressure will rise without the engine running. I postulated that the solenoid valve was open and allowing oil from the accumulator to backfeed the system. I was told I was wrong. However, I have further observed that the higher the oil pressure is on shutdown, the higher the pressure observed on the next start. The theory was that a failing accumulator would have the same symptoms as failing variators. I tend to agree with this. Hope this helps..Ed

I don’t think the oil pressure would be retained for long in the accumulator, I was under the impression it was to stored pressure / supply for when there is sudden demand by the variators with the engine running.

one way to check would be to loosen the supply pipe to either variator (which is very easy to access) and see if there is any oil pressure after shut down for an hour or so.
 

ScottGT

New Member
Messages
5
My car also only does this when it's cold as soon as its warm it fires with no noise at all apart from the lovely sound of the v8.

It seems I have no one local who can do the cam cap modification.

Does anybody know how to do the modification I am an engineer and am in contact with many great machine shops which could do the work for me if I could tell them what to do?

Thanks

Scott
 

ChrisQP09

Member
Messages
2,994
Does anyone know for certain of a case thats resulted in engine failure if not attended to? I think it depends a lot on temperture. The slight rattling occurs 9/10 when cold weather is about. I sometimes get it during colder spells but above 12c, no such problem occurs.
 

conaero

Forum Owner
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34,594
If left the lack of oil supply to the variators themselves will wear and have to be changed which is a front cover off job and far more expensive than the cap mod fix.

The variators themselves reside at the timing chain end of the camshaft.

If left further then the worn variators will reach a terminal fail state where they will seize and/or grenade.

Both of which will result in catastrophic engine failure.

I can only surmise that the timing chain would rip off, possible snap of the cam shaft and will result in the valves and pistons ‘kissing’ and lots of metal debris in the engine.
 
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Wanderer

Member
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5,791
If left the lack of oil supply to the variators themselves will wear and have to be changed which is a front cover off job and far more expensive than the cap mod fix.

If left further then the worn variators will reach a terminal fail state where they will with seize or grenade. Both of which will result in catastrophic engine failure.
Can I just ask again for my own sanity, is the DS wet sump variator noise a different symptom from the 4.7 wet sump after engine number whatever issue?

Started mine up from cold today 9c - no noise. I know like others as summer approaches it won't return. But, Oct - Mar it comes back on cold mornings. Has to be a different issue. Maybe expansion/contraction, col oil, water oil.

I'll start mine now - it's been stood since 10 am, 8c here - I reckon no noise....

I'll be back!!
 

conaero

Forum Owner
Messages
34,594
You will also have dry sump, combined oil water pump and no 2nd stretch belt on the front of the engine and it’s not affected.

Dry sump 4.2’s that do show signs of variator noise is usually attributed to failed solinoid valves on the variator caps.

We have one in at the moment with this issue.
 

Wanderer

Member
Messages
5,791
DS QP is the dry sump 4200 engine.

You have red cam covers yes?
Yes, red covers, and as promised, here's a quick vid just now - no start today actually and no variator noise at all, engine cold, temp gauge on bottom. Previous start up was yesterday 9:00am.

 

ChrisQP09

Member
Messages
2,994
Very confused here! My 4.7s has red cam covers? I get the rattle in colder weather.

Is the red covers the dry or wet sump?