P38A V8 Not starting after head gasket change

Changed HT leads and plugs today. Running a lot better, but still rough. Could lack of valley gasket seals be causing it?

It's not going to be too happy with them missing. You've got 4 v shaped gaps messing with your crankcase pressure.

d1s said:

Changed HT leads and plugs today. Running a lot better, but still rough. Could lack of valley gasket seals be causing it?

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hi ,you might have a dodgy camshaft sensor,might be worth a try?

It was running fine before HGs were changed, I can't imagine something would have gone bad in the mean time. Can unmetered air enter through the ends of the valley gasket?

d1s said:

It was running fine before HGs were changed, I can't imagine something would have gone bad in the mean time. Can unmetered air enter through the ends of the valley gasket?

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Cant see how. It would just enter crankcase. What do you mean as 'rough' running?

Could you upload a short video to you tube so we can get an idea of how she sounds? Does she drive at all?

She drives but the idle is very shakey. More than it was before the head gasket was changed. It's misfiring but I don't know why.
I'll see if I can get a video tomorrow.
I think the injectors are connected in the wrong order, but my mechanic has assured me otherwise.

I've been following this and have no mechanical sounding to comment really.

Is this not a timing issue?

A shaky idle suggests the leads are mismatched!

I would check your coil packs are connected in the correct order as it is SO easy to get two mixed up (or worse).

My guess is you may have muddled two (or more) of the leads on the coil packs because they as so bloomin hard to get at.

I ended up removing the manifold so I could get at the coils, changed them all and found my mate had mixed two up. Once they were done right she ran sweet as.

When I initially picked her up, she ran like a bag of nails, but she started and drove! Mice had chewed through 3 of the leads...

Anyway, I would deffo check the numbers again, just to be sure.

Failing that, you should get the fuel values checked out as she could need a re-trim. But check out the "free to check" stuff yourself 1st.

It is a gems. This problem described could be caused by a cracked flex plate.

Check the old crank sensor for any damage.

Each coil pack contains two coils, pack 1 feeds 2-3-5-8. Pack 2 feeds 1-6-4-7. The system works on the lost spark principle. Two plugs on each coil are fired at the same time. One when a cylinder is on compression and the other when the cylinder is exhausting. So for instance if cylinder 2 is on compression and cylinder 3 is on exhaust, coil pack 1 will fire the plugs on cylinders 2 and 3. And so on and so forth. If the leads are interchanged this will not happen and rough running will take place. Cylinder locations are Left bank 1-3-5-7. Right bank 2-4-6-8 Left being left side of engine as viewed from drivers seat. Number one cylinder is left side of engine at front or crank pulley end.

Rick-the-Pick said:

It is a gems. This problem described could be caused by a cracked flex plate.

Check the old crank sensor for any damage.

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He says it's Motronic.

Leads were fitted as per a diagram I found online, although the injectors are connected (semi)-randomly so I'm sure it's those. I'll have another fiddle tomorrow when the weather is nice.
Thanks for all of your suggestions

err i think i may see your problem..

the cylinder numbers are low numbers front, high numbers by the firewall. odd right, even left..



getting the leads ass backwards will make it run like it **** for sure !!

ukadamwest said:

err i think i may see your problem..

the cylinder numbers are low numbers front, high numbers by the firewall. odd right, even left..

getting the leads ass backwards will make it run like it **** for sure !!

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That's what I was thinking! Lets hope he's nailed it, good call Adam. Beat me to it I learned from experience

d1s said:

Leads were fitted as per a diagram I found online, although the injectors are connected (semi)-randomly so I'm sure it's those. I'll have another fiddle tomorrow when the weather is nice.
Thanks for all of your suggestions

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Connected wrong then. Radiator should be in front of 1 and 2 .

Just picked it up from the MOT centre. Passed, but temperature gauge when straight to red on the way home. Pulled over, steam everywhere, opened coolant filler cap and the water exploded out. Filled it with 5 litres of water, locked it and left it for the night.
Head gaskets maybe damaged again?

d1s said:

Just picked it up from the MOT centre. Passed, but temperature gauge when straight to red on the way home. Pulled over, steam everywhere, opened coolant filler cap and the water exploded out. Filled it with 5 litres of water, locked it and left it for the night.
Head gaskets maybe damaged again?

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In post #84 you say it was running fine before you changed head gaskets. Why did you change them? You obviously have little idea what you are doing.

d1s said:

Just picked it up from the MOT centre. Passed, but temperature gauge when straight to red on the way home. Pulled over, steam everywhere, opened coolant filler cap and the water exploded out. Filled it with 5 litres of water, locked it and left it for the night.
Head gaskets maybe damaged again?

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or cracked block

Running fine, as in not misfiring. Water leaking from rear of the head