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Diesel engine compression tester


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Now I have had my engine rebuilt, I am planning to add testing the cylinder compression to my list of regular checks (every year or two). 

 

Does anyone have any views on a good testing kit, please? This looks like what I need on E-bay, only £35. I'll want to use the glow plug option.

https://www.ebay.co.uk/itm/262940637369

 

Many thanks.

 

[The case looks similar case to the coolant pressure tester I bought in January (a very reassuring piece of kit - pump it up to 15 psi and leave it for 30 mins).]

 

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1 hour ago, Scholar Gypsy said:

Now I have had my engine rebuilt, I am planning to add testing the cylinder compression to my list of regular checks (every year or two). 

 

Does anyone have any views on a good testing kit, please? This looks like what I need on E-bay, only £35. I'll want to use the glow plug option.

https://www.ebay.co.uk/itm/262940637369

 

Many thanks.

 

[The case looks similar case to the coolant pressure tester I bought in January (a very reassuring piece of kit - pump it up to 15 psi and leave it for 30 mins).]

 

I am afraid my answer would be why? If it starts OK from very cold, makes little smoke, and develops the proper power than the compression will be good enough. I am sure that tester should be OK as long as it can handle 500 psi or more.

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7 minutes ago, Tony Brooks said:

I am afraid my answer would be why? If it starts OK from very cold, makes little smoke, and develops the proper power than the compression will be good enough. I am sure that tester should be OK as long as it can handle 500 psi or more.

Yes, that is a fair point. The warning signs were there earlier in the year, cold starting got rather harder than it used to be. Part of the answer is that the engine manual says I should test  this every 800 hours. Another part is that I like gadgets.... 

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6 minutes ago, Scholar Gypsy said:

Yes, that is a fair point. The warning signs were there earlier in the year, cold starting got rather harder than it used to be. Part of the answer is that the engine manual says I should test  this every 800 hours. Another part is that I like gadgets.... 

I just knew it would be something like liking gadgets but why not, it will do no harm.

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With a petrol engine you can spin it on the starter with the plugs disconnected so no danger of it firing up, but with diesel if there is unburnt fuel in the cylinder then it could ignite during cranking and I not sure what would happen to the compression tester.  But maybe in reality it doesn't happen.  Anybody know if there is a risk??

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2 minutes ago, Chewbacka said:

With a petrol engine you can spin it on the starter with the plugs disconnected so no danger of it firing up, but with diesel if there is unburnt fuel in the cylinder then it could ignite during cranking and I not sure what would happen to the compression tester.  But maybe in reality it doesn't happen.  Anybody know if there is a risk??

You do it with the stop control operating even if it is a bit of a faff. When set to stop you get no fuel delivery.

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I bought that one when I was doing up a spare BMC 1.5. It works okay. Dunno about diesel left in the cylinders exploding. I never had that problem but then I checked the compressions with all the injectors out.

 

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9 hours ago, Scholar Gypsy said:

Thanks for comments everyone.  I will report further in a few weeks.  There are some good YouTube videos of course,  which do stress the importance of disconnecting the fuel start solenoid or (in my case) keeping my finger on the engine stop button

If its a Beta I would make up a little hooked piece of coat hanger to hold the mechanical linkage in the stop position. Rather harder on at least some Vetuses because their manual stop needs a diaphragm pressing but maybe a short length of wood wedged between the stop diaphragm and seem engine part.could do the job.

 

Energise to stop solenoids tend to get rather hot if left energised for too long and then the Beta type can get very sticky.

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2 hours ago, Tony Brooks said:

If its a Beta I would make up a little hooked piece of coat hanger to hold the mechanical linkage in the stop position. Rather harder on at least some Vetuses because their manual stop needs a diaphragm pressing but maybe a short length of wood wedged between the stop diaphragm and seem engine part.could do the job.

 

Energise to stop solenoids tend to get rather hot if left energised for too long and then the Beta type can get very sticky.

Thanks - good to know. It's a Mitsubishi, so with the rubber diaphragm. I will either use my thumb, or make up a piece of wood to wedge against the bell housing..

For the latter I think I would need a lathe and a router  .... And so on.

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On 11/09/2018 at 15:53, Furness said:

It does look ok.  Petrol engines are between 150-200 psi,I guess a diesel will be double that.

If it works ok,please let us know.

Yes, worked fine. The only odd bit in the instructions was that it said to a) ensure the fuel supply is cut off (as discussed in other comments) and b) have the throttle lever fully open.

 

I can't see the point of the latter, unless it might do something to the turbocharger to assist the air flow??  [I can't find the turbocharger on my engine ....]

 

DSC_7463.JPG.46ea21fe8ffe8f96d607475ab319b7ae.JPG

 

 

Edited by Scholar Gypsy
Incompetence
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22 minutes ago, Scholar Gypsy said:

Yes, worked fine. The only odd bit in the instructions was that it said to a) ensure the fuel supply is cut off (as discussed in other comments) and b) have the throttle lever fully open.

 

I can't see the point of the latter, unless it might do something to the turbocharger to assist the air flow??  [I can't find the turbocharger on my engine ....]

 

 

 

 

Maybe this instruction was an accidental carry-over from the instruction manual for a petrol engine compression tester?. I do also half remember that one or two diesel engines do have a throttle which is used to control emissions, however it would probably be ECU controlled rather than mechanically linked to any accelerator pedal, and not likely to be found on a narrowboat engine.

 

...............Dave

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8 minutes ago, Mike Hurley said:

Extremely unlikely to have a turbo on a narrowboat engine i would have thought.

Indeed. I know I haven't got one.

 

1 minute ago, dmr said:

Maybe this instruction was an accidental carry-over from the instruction manual for a petrol engine compression tester?. I do also half remember that one or two diesel engines do have a throttle which is used to control emissions, however it would probably be ECU controlled rather than mechanically linked to any accelerator pedal, and not likely to be found on a narrowboat engine.

 

...............Dave

Yes, I wondered about that too. I don't have anything that controls emissions, either ...

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Actually there are still a few diesels around with pneumatic governors like early BMC 2.2s and larger. These have a throttle butterfly so should be tested with the butterfly fully open. Otherwise I can't see the relevance of that particular instruction on more modern engines.

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