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[Derek_in_Penzance]

I nearly posted this on that thread but then thought better of it.

The cylinder head photo on that thread prompts me to ask how common is it for one of the head gaskets to blow a leak between two cylinders, ie at the narrowest point between the bores?

I think my 3.0 Omega estate is suffering from this, as I have low compressions on two adjacent cylinders, but no sign of excessive coolant pressurisation or oil in water/water in oil. It runs very rough -like a bag of nails in fact.

This follows up my thread on this problem some weeks ago -I've been too busy to take the engine apart, although I must do so soon so that I can fix the problem and get my LPG estate back on the road.

[Kevin Wood]

As head gaskets go it's not uncommon for them to fail between pots but it's rare for V6 head gaskets to go full stop. If the fire rings go here they are a little way away from the water jacket so that may well remain intact.

Compression tests aren't that conclusive unless the compression is seriously down or non-existant. How badly down are those 2 cylinders? Do they recover if you chuck some oil in the bores?

Kevin

[Derek_in_Penzance]

this is what I posted oon 7th September!

  Re: Lambda sensor low voltage -car broken down -help!
Reply #11 - 07. Sep 2008 at 19:40    Bugger. I'm sure the leads were causing problems but that just masked the real one.

Compression readings (with Snap-on gauge):

1) 210 psi
2) 180
3) 210
4) 65
5) 215
6) 75

Cranks over quickly on the good readings, slow on the bad, with a squishing sound. Chemical test for head gasket/combustion gasses in coolant is negative. So I conclude that L/H head gasket is leaking between cylinders 4 and 6. That is really annoying, because the head gasket on that side was supposed to have been replaced only 30,000 miles ago. Obviously not very well.

The saga continues. I'm fed up with working on this car.

On reflection, maybe I'll just buy another Omega and hope my luck turns better.

<Browses eBay>.  

[Kevin Wood]

I'd say those readings are fairly conclusive!

Kevin

[Entwood]

this is what I posted oon 7th September!

  Re: Lambda sensor low voltage -car broken down -help!
Reply #11 - 07. Sep 2008 at 19:40    Bugger. I'm sure the leads were causing problems but that just masked the real one.

Compression readings (with Snap-on gauge):

1) 210 psi
2) 180
3) 210
4) 65
5) 215
6) 75

Cranks over quickly on the good readings, slow on the bad, with a squishing sound. Chemical test for head gasket/combustion gasses in coolant is negative. So I conclude that L/H head gasket is leaking between cylinders 4 and 6. That is really annoying, because the head gasket on that side was supposed to have been replaced only 30,000 miles ago. Obviously not very well.

The saga continues. I'm fed up with working on this car.

On reflection, maybe I'll just buy another Omega and hope my luck turns better.

<Browses eBay>.  

That bit has me puzzled ....   .. if the compression is down due to gas leakage .. it should be the opposite way round ?? faster on low compression, slower on high

If the problem is due to knackered valves, or valves opening at the wrong time, the "squishing" sound may be contact ?? or one cylinder "feeding" another ?? which might explain the harder work on low compression .. but I'm not sure ...

Given that the whole of that bank is lower than the other .. could it be one bank of cams way out

Just seems a tad strange to me .. harder work at low compression .. can't get me head around that bit ... but what do I know ...  

[The Red Baron]

Tiss a bit odd that, could it be broken rings, hence the strange noise?. :-?

[Kevin Wood]

this is what I posted oon 7th September!

  Re: Lambda sensor low voltage -car broken down -help!
Reply #11 - 07. Sep 2008 at 19:40    Bugger. I'm sure the leads were causing problems but that just masked the real one.

Compression readings (with Snap-on gauge):

1) 210 psi
2) 180
3) 210
4) 65
5) 215
6) 75

Cranks over quickly on the good readings, slow on the bad, with a squishing sound. Chemical test for head gasket/combustion gasses in coolant is negative. So I conclude that L/H head gasket is leaking between cylinders 4 and 6. That is really annoying, because the head gasket on that side was supposed to have been replaced only 30,000 miles ago. Obviously not very well.

The saga continues. I'm fed up with working on this car.

On reflection, maybe I'll just buy another Omega and hope my luck turns better.

<Browses eBay>.  

That bit has me puzzled ....   .. if the compression is down due to gas leakage .. it should be the opposite way round ?? faster on low compression, slower on high

If the problem is due to knackered valves, or valves opening at the wrong time, the "squishing" sound may be contact ?? which might explain the harder work on low compression .. but I'm not sure ...

Just seems a tad strange to me .. harder work at low compression .. can't get me head around that bit ... but what do I know ...  

Yes, me too. If it's only building 65 PSI under the compression tester it shouldn't load the starter motor anything like as much as the other pots. Only thing I can think of (and this is a really long shot) is that the inlets on that pair aren't opening at all, meaning the starter is having to overcome a vacuum on the induction stroke.

So, inlet camshaft snapped between cylinders 2 and 4? I said it was a long shot.... :-?

Either way, it needs to come apart for an exploratory..

Of course, if the bearing caps were fuddled up when they changed the head gasket it's not impossible.

Kevin

[Entwood]

Might be worth whipping the cam covers off to have a look ?? easier than taking the heads off .. and a check of the cam belt/timing again .. easier than a head off  ..

[v6coop]

Of course, if the bearing caps were fuddled up when they changed the head gasket it's not impossible

or not torqued down properly and have come loose allowing the cam shaft to rise in the carrier reducing clearance? Alternatively could it be cam followers not filling?

[Derek_in_Penzance]

Thank you to all who have contributed and I'm sorry I haven't kept tabs on this thread today -been busy under a car! (not mine though).

When I start this job I will update you all as it progresses, and I will post photographs. The engine definitely seemed to have a struggle turning over when I had the compression tester in either of the two affected cylinders, compared to the other four, when it just whizzed around in the usual way. I found it really odd. I'm a newbie to V6s so this is very much a learning curve, although I know the CIH straight sixes inside out. I've never experienced anything quite like it!

[Derek_in_Penzance]

OMG, I've just looked through all two million pages of the PDF engine rebuild guide on this site and it looks pretty daunting. Think I need to stick to the straight sixes!

As my gearbox is almost duff I'm planning to take the whole engine and gearbox out so that I can work on it in comfort in the workshop, and not have to lean over the engine bay all the time.
Anyway, you never know, maybe the head(s) don't need to come off, but I know that is probably just wishful thinking.

[Andy B]

OMG, I've just looked through all two million pages of the PDF engine rebuild guide on this site and it looks pretty daunting. Think I need to stick to the straight sixes!

As my gearbox is almost duff I'm planning to take the whole engine and gearbox out so that I can work on it in comfort in the workshop, and not have to lean over the engine bay all the time.
Anyway, you never know, maybe the head(s) don't need to come off, but I know that is probably just wishful thinking.

You could always do as Graham C/Omegatoy did .... and put a straight 6 in!!! A C30SE would suffice ... you don't need a 3.6 Lotus.  

[Derek_in_Penzance]

OMG, I've just looked through all two million pages of the PDF engine rebuild guide on this site and it looks pretty daunting. Think I need to stick to the straight sixes!

As my gearbox is almost duff I'm planning to take the whole engine and gearbox out so that I can work on it in comfort in the workshop, and not have to lean over the engine bay all the time.
Anyway, you never know, maybe the head(s) don't need to come off, but I know that is probably just wishful thinking.

You could always do as Graham C/Omegatoy did .... and put a straight 6 in!!! A C30SE would suffice ... you don't need a 3.6 Lotus.  

Yes, it's something I've thought of already, especially as I have a workshop with oh, about six C30SE engines lying around -all with head gaskets gone!

[Andy B]

OMG, I've just looked through all two million pages of the PDF engine rebuild guide on this site and it looks pretty daunting. Think I need to stick to the straight sixes!

As my gearbox is almost duff I'm planning to take the whole engine and gearbox out so that I can work on it in comfort in the workshop, and not have to lean over the engine bay all the time.
Anyway, you never know, maybe the head(s) don't need to come off, but I know that is probably just wishful thinking.

You could always do as Graham C/Omegatoy did .... and put a straight 6 in!!! A C30SE would suffice ... you don't need a 3.6 Lotus.  

Yes, it's something I've thought of already, especially as I have a workshop with oh, about six C30SE engines lying around -all with head gaskets gone!

That's what I thought! You had an 12v engine mountain outside in the yard when I paid you a visit.

[Derek_in_Penzance]

OMG, I've just looked through all two million pages of the PDF engine rebuild guide on this site and it looks pretty daunting. Think I need to stick to the straight sixes!

As my gearbox is almost duff I'm planning to take the whole engine and gearbox out so that I can work on it in comfort in the workshop, and not have to lean over the engine bay all the time.
Anyway, you never know, maybe the head(s) don't need to come off, but I know that is probably just wishful thinking.

 

I still have! Go on forever, so nobody ever wants one

You could always do as Graham C/Omegatoy did .... and put a straight 6 in!!! A C30SE would suffice ... you don't need a 3.6 Lotus.  

Yes, it's something I've thought of already, especially as I have a workshop with oh, about six C30SE engines lying around -all with head gaskets gone!

That's what I thought! You had an 12v engine mountain outside in the yard when I paid you a visit.