Technical Compression Testing a Multipla

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Technical Compression Testing a Multipla

Sunroofjo

Eat. Sleep. Multiplas.
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Hello! I wonder if anyone can help answer this question...
Our son has been very busy of late, working on the multipla engine and replacing many bits and pieces (sorry, not very technical…) and anyway, we are now at the stage where the engine is back in the car and it won't start. Anyway, we have a really lovely neighbour helping with the project at this stage, but multiplas are outside of his expertise and we could do with some of that very specialist advice right now! Here's where we are at:

We have fuel, and we have air, and it will 'run' on fast start but isn't running on diesel.
The injectors seem to be working and compression is suspected as being the reason for the non running.

I have purchased a diesel compression testing kit, and we have this out of the box, but… it doesn't seem to be long enough to be able to do the test.
(see photo) showing that with the various clamp and sleeves in place, there isn't sufficient room to get the hose on to test it.

Can anyone tell us how to go about carrying out a compression test with one of these kits? …We would be ever so grateful.
 

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Hi,
was it running before parts replaced?
When the key is first turned on does the imobiliser key code light come on briefly?
 
Hi,
was it running before parts replaced?
When the key is first turned on does the imobiliser key code light come on briefly?
Hi Jackwhoo! Thanks for your reply, it was running before parts replaced - but very poorly, and wouldn’t go up hills.
And the question of the immobiliser was ruled out as it would run albeit it briefly on the spray can, so thats not thought to be the issue…
 
I couldn't see your video but It will run if fuel sprayed into air intake even if immobilser active.

If you do get it running don't run it for more than a few seconds with no coolant .
 
Thanks Jack, I will relay your immobiliser thoughts to the mechanics! Its definitely worth double checking though, as we are a bit stuck as things stand…
 
I see a lot of work has been done ,double /triple check all the engine sensors have be reconnected. Especially the crank shaft sensor between back of engine and bulkhead.
 
Just a thought, but if you have disturbed the parts of the injectors, if so try doing a leak off test on each injector.
With common rail engines if one injector has a high leak off to the return then the fuel cannot reach the pressure to run the engine, unlike older diesels where you could even have one injector out of the engine and it would still run on the other three.
 
Just a thought, but if you have disturbed the parts of the injectors, if so try doing a leak off test on each injector.
With common rail engines if one injector has a high leak off to the return then the fuel cannot reach the pressure to run the engine, unlike older diesels where you could even have one injector out of the engine and it would still run on the other three.
Thanks Mike,
I’ll pass that onto the mechanics (sorry… I am just the messenger tonight!) thanks again, Jo
 
Thanks Mike,
I’ll pass that onto the mechanics (sorry… I am just the messenger tonight!) thanks again, Jo
I don't think the compressions are the issue from the sound of it running on easy start. Generally if compressions are low but everything else is OK then you get lots of smelly white smoke from the exhaust which is unburnt fuel as insufficient compression heat to ignite the fuel.
 
I don't think the compressions are the issue from the sound of it running on easy start. Generally if compressions are low but everything else is OK then you get lots of smelly white smoke from the exhaust which is unburnt fuel as insufficient compression heat to ignite the fuel.
Ahh… that sounds like good news to me Mike! Thank you… it gives some hope that tomorrow might be alright after all…!
 
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