TD42 compression results - too high???

[Mark2]

Last night I used my new ebay diesel compression tester for the first time. I used the adaptor for the glow plug fittings - easier than removing injectors.

I got results on the TD42 of between 430 and 480 psi. This seems to be higher than maximum the figures specified in the manual?? Could it be due to carbon in the combustion chambers? Anyone else tested a TD42 recently?

My 'procedure' involved cranking the engine until untill the guage woudnt climb any higher - maybe 6-8 revolutions?? (maybe more). This is how I've previously done it on petrol engines, is it any different for a diesel?

[bogged]

Last night I used my new ebay diesel compression tester for the first time. I used the adaptor for the glow plug fittings - easier than removing injectors.

I got results on the TD42 of between 430 and 480 psi. This seems to be higher than maximum the figures specified in the manual?? Could it be due to carbon in the combustion chambers? Anyone else tested a TD42 recently?

My 'procedure' involved cranking the engine until untill the guage woudnt climb any higher - maybe 6-8 revolutions?? (maybe more). This is how I've previously done it on petrol engines, is it any different for a diesel?

dont know the answer, but how do you stop it from starting? mine starts after 2 turns.

[InSanE]

check your valve clearances mate they may be to tight.

[MyGQ]

dont know the answer, but how do you stop it from starting? mine starts after 2 turns.

to stop it from starting, you pull the power plug from the diesel pump, this keeps the diesel cut solinoid in the off positions and prevents it from getting fuel, thus no fuel gets injected into the engine, its the same way the engine gets turned off by the key

[Mark2]

check your valve clearances mate they may be to tight.

Been meaning to check the valve clearances for a while.....

I'm not trying to be smart but how would tight valves cause the compression to be too high? If they were super tight, the valves wouldnt close properly right? so compression would be low? Not saying you're wrong, but I want to understand this.

[marko]

check your valve clearances mate they may be to tight.

Been meaning to check the valve clearances for a while.....

I'm not trying to be smart but how would tight valves cause the compression to be too high? If they were super tight, the valves wouldnt close properly right? so compression would be low? Not saying you're wrong, but I want to understand this.

Your right, tight valve clearace will give low figures. How much higher than spec is it. Did you get the eng to operating temp fisrt?

[Mark2]

check your valve clearances mate they may be to tight.

Been meaning to check the valve clearances for a while.....

I'm not trying to be smart but how would tight valves cause the compression to be too high? If they were super tight, the valves wouldnt close properly right? so compression would be low? Not saying you're wrong, but I want to understand this.

Your right, tight valve clearace will give low figures. How much higher than spec is it. Did you get the eng to operating temp fisrt?

I think it was about 50 PSI over spec. Engine was barely warm. So not at operating temp - but this would usually give a lower result in my experience.

[ausoops]

can you compare your results using your tester to someone elses? if its an ebay job it may be out of calibration.

[Dzltec]

Mark 2, the figures are ok. Did you do it with the stop solenoid disconnected? If it was done with fuel in it it will be higher.

What problem are you chasing? The guage may also be slightly inaccurate.



Andy

[Mark2]

Mark 2, the figures are ok. Did you do it with the stop solenoid disconnected? If it was done with fuel in it it will be higher.

What problem are you chasing? The guage may also be slightly inaccurate.



Andy

Its a 2nd hand engine I've bought to replace an overheated engine - I just wanted to make sure it was OK before fitting it and swapping the turbo etc over (should have tested it before buying it I suppose). I tested it with the plug to the fuel pump disconnected. Sounds like theres not too much too worry about (something I'm good at)

[Yom]

As long as the results are even and no major fluctuations then its ok.

[bogged]

dont know the answer, but how do you stop it from starting? mine starts after 2 turns.

to stop it from starting, you pull the power plug from the diesel pump, this keeps the diesel cut solinoid in the off positions and prevents it from getting fuel, thus no fuel gets injected into the engine, its the same way the engine gets turned off by the key

So this is your Kill Switch in a diesel then?

[twodiffs]

dont know the answer, but how do you stop it from starting? mine starts after 2 turns.

to stop it from starting, you pull the power plug from the diesel pump, this keeps the diesel cut solinoid in the off positions and prevents it from getting fuel, thus no fuel gets injected into the engine, its the same way the engine gets turned off by the key

So this is your Kill Switch in a diesel then?

yep - thats one way bogged, the engine just turns over and doesn't fire...but ahem..enough of that on the net

[Wrench_Pilot_86]

you have any information on the 2nd hand engine's past cause it might of had a freshen up before you got it, also when i have done comp checks at work the tester is fitted into the injector hole rather than the glow plug one, (being Toyo's the a bit different)

[Mark2]

you have any information on the 2nd hand engine's past cause it might of had a freshen up before you got it, also when i have done comp checks at work the tester is fitted into the injector hole rather than the glow plug one, (being Toyo's the a bit different)

It was a while ago now but its been running well since - no idea on the past history. Hasnt used any oil/water in 5000k's. Still have to get it dyno turned as the pump timing was a bit of a guess when I swapped the aneroid pump over.

Glow plug's on a TD42 are a lot easier to remove than injectors, dont know if this changes the compression readings - wouldnt think it would.

My procedure was disconnect fuel solenoid, remove all glow plugs, crank till max reading achieved, cant remember how many turns this took, not that many I think.

[A.J.]

Hey Mark2 where are you mate? If you are in Sydney, I'd come over with my TD42 to cross-reference. I want to check the compression anayway before I put on the turbo