Poor low speed running & pressure test

[DEREK SLINGSBY]

Do you think I need to take the head off and check the valves or look!
The problem starts at the bottom and works up.

Just done a compression test, 4 185psi, 3 185, 2 170 and 1 165.

Had the rocker cover off to check the valve clearances, should be IN 0.15 OUT 0.2, they were 0.9-0.7,0.5-0.25,0.13-0.22 & No 4 was 0.11-0.15.

Changed leads, plugs, dist cap, rotor arm & still it judders badly in 4th below 70kmph but ticks over and runs fast ok. Pipes on carb checked too.

If I pull leads 1 & 2 off together it runs and sound the same, pull 3 or 4 off and it stalls.

Renault 4 GTL 1993 runs ok under load & at reasonable speeds but under no load it judders really bad at 30mph.

 

[harbourseal]

Have you adjusted the valve clearance?
Maybe adjust them an try the pressure test again. Then you might be able to make up your mind about lifting the head.

 

[mr-reno-139]

Inlet manifold gasket most likely check nuts as if loose or fall off causes bad running VERY common but often overlooked
Unless compressions more than 10 per cent difference I wouldn't worry but always worth remembering slightly loose tappets /valve clearance safer for unleaded fuel
Tight will burn valves out cause poor idling etc

 

[DEREK SLINGSBY]

Have you adjusted the valve clearance?
Maybe adjust them an try the pressure test again. Then you might be able to make up your mind about lifting the head.

Thanks, I did but will check them again.

 

[DEREK SLINGSBY]

Inlet manifold gasket most likely check nuts as if loose or fall off causes bad running VERY common but often overlooked
Unless compressions more than 10 per cent difference I wouldn't worry but always worth remembering slightly loose tappets /valve clearance safer for unleaded fuel
Tight will burn valves out cause poor idling etc

I'm really at a loss so will re check the valves and the inlet manifold, I just want to find something wrong and it's so frustrating. It may have to wait as my daughter has taken my Peugeot 307 down to Portugal and is calling me with car problems too.

 

[DEREK SLINGSBY]

Raise the flags and break out the booze, she's fixed, the poor running was caused by a split in the inlet manifold gasket. She runs like a dream, I'll post some pics when I get them off the phone.

 

[DEREK SLINGSBY]

Not sure if this gasket was ever correct, it looks like the hole for the stud was in the wrong place and someone modified it. It looks like it had leaked round the stud and in as well as in the bottom centre where it appears was split too.

 

[Jurjenz]

It does look a bit weird indeed. Thumbs up that you found the problem!

 

[mr-reno-139]

After 40 years working exclusive on renaults not much escapes me ☺