Rb20det Compression Test

[Carlos.pereira]

Rb20det compression test. A tad off operating temp. Results from camcover to firewall. 140ps.140ps.130ps.135ps.135ps142ps. Is that a bad reading ? Motor has done 140ks. Reason for testing is it has recently started to smoke badly .whiteish smoke

[Ben C34]

Fine

[jiffo]

Bloody hell Ben, not for me.

Those 140,000k's, must have been hard yakka.

My old 20 had well over 250,000k's and she still blew 150 to 155. Any less and they're rubbish off boost.

[KiwiRS4T]

Did you do a wet test as well? Numbers are good enough (within 10) . Its probably done a few more than 140,000

[Dose Pipe Sutututu]

if you're low on power add boost!

[jiffo]

Yes John you can still make reasonable power by adding boost, even from those numbers.

But it's off boost where power and economy suffers, and a 20 needs everything going for it.

Remember also, a stock 20 is rebuild time at around 130psi.

[Kustom20]

Rb20det compression test. A tad off operating temp. Results from camcover to firewall. 140ps.140ps.130ps.135ps.135ps142ps. Is that a bad reading ? Motor has done 140ks. Reason for testing is it has recently started to smoke badly .whiteish smoke

Has the engine had new oil put in? If so what brand and weight? Maybe check your oil pressure and turbo seals, is it constant smoke if the plugs are fouling up would be a sign of combustion chamber oil you could eliminate the source of the oil burning up by possibly checking plugs.

140K shouldnt be too bad on the rings though depending on how hard the vehicle has been driven. If it is rear turbo seal then it wouldnt be combustion chamber and you should see signs of oil leak on the rear of the turbo. Oil pressure to the turbo cant exceed otherwise it can pass the seal.

Have you done anything to the engine or did it just start to slowly get more smoke? Or did it just start smoking bad all of a sudden? Has the vehicle overheated could even be a head gasket between the oil journals or returns. If this was the case you would be seeing more blow by as the number 3 appears to be 10 to 12 below the highest reading.

Could even be valve stem seals or depending on the smoke color if it is white then it seems more like moisture/water blueish is oil being burnt.

Maybe post up some more findings and can help narrow it down.

Is it constant cold start or when it gets more to operating temp?

Hope this helps

[Missileman]

did a comp test on a genuine 90K stock motor rb20det just recently, 160-165 PSI across the lot, no smoke at idle but has a puff when you first come on boost but clears an does not return unless you get caught in traffic.

[jiffo]

For that engine Missleman I'd suggest valve stem seals are in need of replacement.

They get hard as wood and eventually disintegrate.

Having said that, I'm a firm believer that unless you're totally in love with your 20, any engine overhaul is money wasted. Better to drop in something newer.

Do the sums just for a full gasket set and you're halfway towards a newer/bigger capacity donk.

[tridentt150v]

Whiteish smoke ....not coolant/water is it?

[Kustom20]

Grey or Blue Smoke = Engine Oil Burning

Valve Stem Seals - Turbo Seals - PCV Blocked - Valve Stem Guides - Piston Rings

Compression or Leak Wet Test - Compression can also be down from Leaking Valve or Piston Rings - Cam Lobe rounded not allowing valve to open the same as others hence lower comp reading. Checking these with comp test and wet test or leak test will determine which parts are allowing comp leak

White Smoke = White smoke (Steam) or water/coolant/antifreeze vapor from the exhaust. normally when water vapor heats up it dissipates and not as noticeable if the vapor stays then there is an issue - for Auto vehicles sometimes the trans fluid can enter the intake on some vehicles through the modulator - this also burns at this color and close to grey color

Cracked Head, Cracked Cylinder Block, Head Gasket stuffed between water and cylinder allowing water in and lowering compression - in this case you can see the water movement in the radiator going up and down most times.

When your vehicle is running check the radiator water movement - if it goes up and down then head gasket between cylinder and water jackets

Check your oil cap for coolant/water/antifreeze what ever you want to call it for signs of milky chocolate looking contaminents on the oil cap or dipstick

If its water to oil on the head gasket then obviously the oil cap will be full of milky sludge and eventually the worse it gets you would notice this pretty quickly

Black Smoke = Fuel too rich - can be caused from many things just to list a few, injector issue, blocked air cleaner, sensor issue, ignition problem, FPR stuck,

Obviously any smoke coming from your exhaust is a sign of something not quite right

Edited December 30, 2015 by tuning_vs_hardware