2.5 D n/a compression low

Wotcha Had my 110 engine suffer when the cam belt snapped. cam followers and pushrods all in a bad way. pistons seemed OK and a mechanic mate tested em by sticking fluid on top of them which didn't seep away - apparently a good sign. replaced the head with one off a mate's engine that had been reconditioned a year or so before but his big end bearing had seized. the engine ran but very very smokey - especially on acceleration - and difficult to start i tried all kinds of things - got the injectors serviced (apparently knackered), new glow plugs, new battery, redex in hte tank.....ended up getting a compression test done and 3 cylinders were down to 200 and the other to 210. it needs to be above 300 to start happily I am told. I've checked with the supplier of the head gasket and apparently it's the right one. Has anyone got any ideas/experience of causes of low compression - and tests? I'm at the stage where another engine seems a better idea than rebuilding the engine for various suspected faults and finding they were not the cause. thanks nathan

It is probably worth trying a leak down test on your engine. I've been in a similar situation to you where you wonder where the compression is going and a leak down test will give you an idea of where the compression is being lost. Take it to a garage with the correct equipment and they will plug it in to a compressor with a special calibrated gauge, i think the maximum acceptable loss is about 25-30 percent. The advantage of this method is that it will tell you exactly where the compression is going. If the valves have had it (as in my experience) you will hear the air escaping through the exhaust or inlet port (with the manifold off), or down into the sump where if the rings are knackered or bores are worn. As the values on your engine are similar I would reckon that the bores or rings have worn as these engines usually have to work hard for a living as they're not as powerful as most land rover engines, and especially in a big vehicle like the 110. However you may be lucky and just need a new set of rings and a deglaze. With the engine hot it may be worth taking the filler cap off and see if there is evidence of engine blowby are sure sign that all is not well with the pistions/bores. Although pouring a liquid on to the top of the piston will give an indication of pistion condition in some cases the leak down test is alot more accurate and definate. If all else fails, i've got a 2.5TD engine thats for sale.

Regards, Dave