Compression test

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dag019

dag019

Well-Known Member
Posts
6,099
Location
Warwick
Can anyone recommend me a decent compression tester and associated paraphernalia that will no cost the earth?
It need to be suitable for 2.25 diesel engine primarily, but would be good to have adapters suitable for tdi's. At some point I may get a petrol but currently all of mine and my friends are diesels.
 
j_g_uk said:
If you were near Farnham you could borrow mine.
Click to expand...
Thank you for the offer, unfortunately a little far, I could proabably nearly buy one with the fuel it would cost :D.
I think I have avoided it long enough and it is really something I should have in my tool box, I have most other things now!
 
No problem. I actually bought it to check the compression on the boat engine but discovered it doesn’t have the right fitting for either the injector thread or preheat thread on the Volvo marine engine (a marinised and rebadged Perkins three cylinder.) It does however appear to have the TD5 adapter and it seems a shame for it to sit on my shelf if people nearby want to check and compare compression.
 
Look on Amazon for diesel engine compression testers, there are lots and the prices vary widely. I bought one a few years ago, Chinese but I won't use it very often. It cost about £20 at the time. Not bad when you consider that the local diesel specialist was going to charge me £70 to test my compression and I'm trade.
Edit: My set has an array of adaptors for various engines.
 
Extreedoc said:
Look on Amazon for diesel engine compression testers, there are lots and the prices vary widely. I bought one a few years ago, Chinese but I won't use it very often. It cost about £20 at the time. Not bad when you consider that the local diesel specialist was going to charge me £70 to test my compression and I'm trade.
Edit: My set has an array of adaptors for various engines.
Click to expand...
Thanks, I have looked on ebay and amazon an there seem to be lots of fairly cheap kits avaiable, but i am always dubious of buying cheap tools. So good to know that they are good enough for occasional use.
 
I piad about £28 for a cheap one that had all the daptors I needed and its worked great. Only needed it a few times but it paid for itself already. I would go for a cheap on off e-bay but take some time looking at the pictures to make sure you get the right adaptors, I needed the T bar type for a Perkins, came with the £28 set but not the £25.
 
same here I paid low twenties for an amazon cheapo, as long as it is consistent within itself it will show the problem cylinders even if it isn't as accurate as an expensive commercial tester
 
many thanks all. A cheap tester kit is what I will go for.
Next question is what adapters do I need to make sure it is usable for a 5mb 2.25 diesel and a 200tdi, that way I can make sure I get the right kit?
 
You need to identify the injector threads and length, this should be in the specs or on spare injectors. The 2.25 could be the two bolt type (there seem to be variations) in which case you need the adaptor that looks like an H shape, Google the injectors and see what they look like then look for somethig the same in the box. One reason I went for the set I got was they had a decent high res pic on the web that I could enlarge enough to see the adaptors properly.
 
The killer is difference between cylinders. I called the tech department at Perkins, they were very helpfull. The guy said that with old diesels they did not look at the compression figures in absolute terms, they found many would run fine with 250 - 300 even if they were hard to start, but more than 50 psi differnce was between cylinders was a sure indicator of trouble. Mine had 100 psi differnce and he was right.
 
rob1miles said:
The killer is difference between cylinders. I called the tech department at Perkins, they were very helpfull. The guy said that with old diesels they did not look at the compression figures in absolute terms, they found many would run fine with 250 - 300 even if they were hard to start, but more than 50 psi differnce was between cylinders was a sure indicator of trouble. Mine had 100 psi differnce and he was right.
Click to expand...

Agree completely. we never used to compression test old engines. We just used to start them up, and slacken the injector unions one at a time, to diagnose which was the weakest cylinder. Then try and rectify the fault, starting with simple stuff like the tappets, and going to engine wear of none of the simple things worked.
 
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