Checking compression

[Doug]

Where would I obtain a good quality compression tester for a Yanmar 2gm20f? How much would they be? Could I get a dummy injector fitting that attaches to a standard tester? Are they pretty universal (US, Japan, etc). Thanks.Doug

 

[Gordon Torresen]

Compression tester

Don't try using a "regular" comperssion tester with the adapter for a diesel. Most automotive gauges top out at 300 PSI. Yanmar diesel pressures can approach 600 PSI. You can use a standard, rubber tipped, automotive gage as an indicator. If you can hold it in the hole, your compression is way too low. So far the best compression tester that we have found is by Snap-on, their number MT 33C, sells around $150.00. An adapter is available from Yanmar for about the same price (don't ask). We often machine adapters for the many rare engines that we find in sailboats. I firmly belive that the best compression test is the first start-up of the day. If your engine starts promptly, your compression is good.

 

[Bill Heaton]

Compression Test

I liked Mr Tolleson's comment re the best test is how easy it starts. I obviously have poor compression as I need ether to start easily. My question:is my engine a candidate for complete over haul or what ? Pls clear up another point: my model is,I think,SVE8, yet I keep seeing 2GM20F,2QM15,etc. Am I reading the wrong number ? Its a 1978 Yanmar.