Technical 1.3mjd Compression Test

[Busso]

Hi all,

I'm wanting to do a compression test on a 1.3 multijet but just after some assistance. I've used a low PSI gauge tester I have in the injector holes expecting it to max out past the 300psi but instead I've recorded these figures which the gauge holds steady at. I really don't know why they are so low unless the engine is completely knackered... What should healthy readings on this engine be?


1 - 142 psi


2 - 120 psi


3 - 137 psi


4 - 165 psi

 

[bugsymike]

Hi all,

I'm wanting to do a compression test on a 1.3 multijet but just after some assistance. I've used a low PSI gauge tester I have in the injector holes expecting it to max out past the 300psi but instead I've recorded these figures which the gauge holds steady at. I really don't know why they are so low unless the engine is completely knackered... What should healthy readings on this engine be?


1 - 142 psi


2 - 120 psi


3 - 137 psi


4 - 165 psi

Like you I would expect 300psi plus, I have seen 500psi on some big engined Fords in the past. How accurate is the gauge?
Assuming you are getting a good seal. For a diesel I would use a proper screw in high pressure gauge, and crank for about ten turns on each cylinder. The figures you are getting are not even (165 down to 120!), which sounds like a possible fault anyway.
With figures that low I would expect very poor starting and white smoke (unburnt fuel) when it did start.

 

[Busso]

Like you I would expect 300psi plus, I have seen 500psi on some big engined Fords in the past. How accurate is the gauge?
Assuming you are getting a good seal. For a diesel I would use a proper screw in high pressure gauge, and crank for about ten turns on each cylinder. The figures you are getting are not even (165 down to 120!), which sounds like a possible fault anyway.
With figures that low I would expect very poor starting and white smoke (unburnt fuel) when it did start.

Gauge is only a cheap one so could be wrong but i would expect even numbers at least. The turbo had failed but wanted to check engine before fitting a new one.

Pretty sure it’s a good seal, I used the rubber bung and held in with injector bracket.

 

[bugsymike]

Gauge is only a cheap one so could be wrong but i would expect even numbers at least. The turbo had failed but wanted to check engine before fitting a new one.

Pretty sure it’s a good seal, I used the rubber bung and held in with injector bracket.

As you say "even numbers at least", those seem way out.
No chance of borrowing a decent diesel compression gauge?
Have you been able to look at the old turbo, anything broken off it that got swallowed by the engine?

 

[Busso]

As you say "even numbers at least", those seem way out.
No chance of borrowing a decent diesel compression gauge?
Have you been able to look at the old turbo, anything broken off it that got swallowed by the engine?

I might buy one but the turbo didn't look great. I think the nut has made it's way off the turbine into the engine.

 

[bugsymike]

I might buy one but the turbo didn't look great. I think the nut has made it's way off the turbine into the engine.

I fitted a turbo supplied by a customer (so his liability) on a 308 Peugeot, worked great for a day then the nut ran off the impeller and lost boost, luckily it had stopped in the inlet hose. If only the nut I would have thought if it had got in and jammed a valve open then there would be zero compression on that cylinder. To mess up like you suspect then I was thinking bits of impeller inside the engine. You never know, I learn something new every day.
If no other damage than the nut off couldn't you get a good quality heat proof nut and carefully refit it? To test it could you run it up with the pipe to the engine off and see if it was giving pressure. Keep your fingers out though

 

[Busso]

The turbo is knackered anyway so couldn’t reuse it, maybe new cartridge would be ok. I’d be surprised if the nut made it to the engine past the inter cooler and pipe work bends.

 

[bugsymike]

The turbo is knackered anyway so couldn’t reuse it, maybe new cartridge would be ok. I’d be surprised if the nut made it to the engine past the inter cooler and pipe work bends.

As you say , not likely, so why low compression. Many miles? Recent or suspect cam chain issue? Daughter had the grande Punto 70hp version, mechanically apart from me having to do the timing chain etc. it ran to around 145k before smoking on start up, but still got her to work every day.

 

[Busso]

As you say , not likely, so why low compression. Many miles? Recent or suspect cam chain issue? Daughter had the grande Punto 70hp version, mechanically apart from me having to do the timing chain etc. it ran to around 145k before smoking on start up, but still got her to work every day.

89k suspected cam chain issue. Well it's not suspected anymore. Dropped the sump & found the guide rail in there

Also found the turbo nut in the intake! There was still a fair bit of glitter at the bottom though!

 

[bugsymike]

89k suspected cam chain issue. Well it's not suspected anymore. Dropped the sump & found the guide rail in there

Also found the turbo nut in the intake! There was still a fair bit of glitter at the bottom though!

I worked for a Lada dealer in the 1970s and on dropping the sump on one, I think it was four guides down there, they had a habit of chewing them and the retaining bolts off and people would just fit new guide and carry on. There was a large slipper on the adjuster side, but the little guide was the one that would break off, then the chain would eat into the head.