300Tdi Compession Test

[tweetyduck]

400psi +/- 10% across all cylinders according to the garage. Isn't that a bit high ?

If its even 400 accross all of them, should it be fine?

Been advised to give a good long drive and use it for a few months which is good advice (which i'm going to do) but what do you reccon to the compression figures? The engine is smokey at start and even when revving when warm. I can generate a rather large continuous cloud by dabbing the paddle.

I'll put a 1000 miles on it and then should i just change the injectors and spill (spill needs replacing anyhow) and the glow plugs as maintenance and see if its any better. I'll keep the old ones. BTW the glow plugs are oily according to the garage.

If thats no good then take out the pistons and change the seals and rings etc. Is that a sensible plan?

TA

[western]

RAVE 300tdi manual info for compression test states 348psi on each cylinder in good order +/- 10%

[RustyNissanPrairie]

I did a compression test on my NA a month ago.

Cold engine and results of between 375 and 390 on all 4, apparently all ok according to those who know;

http://www.orrp.com/smf/index.php?topic=53799.msg880739#msg880739

If it struggles to start or is 'lumpy' when its cold and started then its probably a glowplug, otherwise just clean them and put em back in.

What colour smoke?

[tweetyduck]

Black smoke. Worries me its high and oil seems to make it high (Reading between the lines of the link you posted) So oil = high compression and black smoke seems to fit,,, or is that simplistic?

I'm off to get it back on Friday. The Garage have had it a month plus. Time to fix what they have found. Well the minor things that i can do. I'll leave the big stuff to them.

I will certainly clean or replace the glow plugs as advised.

[steve b]

Black smoke is diesel Niell,

to a point you will get that revving stationary as pump/turbo are expecting load = more fuel.

Check for leaks on the intake side between turbo and engine, when was cambelt last done?

Is the EGT still connected?

Cheers

Steveb

[TD5 power]

hi

The compression test results are nothing to worry about it is possible the head has been skimmed at some point which would increase the compression ratio leading to your results, which have a large accuracy range anyway.

Oil can affect the results as it helps the rings to seal, it is common to test a cylinder then add a small amount of oil and repeat the test an increased reading would show the rings or bores are worn.

I think the injector pump has been tweaked too far, black smoke is unburnt fuel so either too much is being delivered (injector pump settings) or the injectors need recon as they are not atomising the fuel correctly.

As above change the glow plugs not expensive and can only help

Matt

[RustyNissanPrairie]

I added the oil to check the difference in piston/cylinder clearances when cold and to see when fully sealed ie with the added oil to determine if I'd needed to do some block work when I change the head.

Black smoke can be incorrect injection pump timing-especially if its 'lumpy' when it starts up due to the timing being retarded too much and injecting on the piston downstroke and cylinder compression pressure not being as high as they should be hence incomplete combustion and smoke, can be mistaken for a faulty glow plug also-again incomplete combustion and lumpy running just after start up.

Or as posted above and a possible tweaked injection pump or dirty injectors.

[tweetyduck]

Thanks guys. Thats made me a lot happier. Can i clean the injectors or should i just replace them? The timings been checked and they say its OK. The turbo has been checked for leaks and its also OK. They also checked for oil in the turbo, also OK.

So black is fuel, white is oil then....i shall remember that!

Cambelt is 500 miles ish and EGT is removed??? (if this is the same as EGR) Sorry for my complete lack of knowledge. The garage mentioned someting EG?? was removed and it was "good". I presume its electronic and no good for overland?

[western]

nope, blueish tinge is oil

excess white smoke is either burning coolant [steam] or a incorrectly adjusted injection system [excess unburnt diesel fuel]

[TD5 power]

hi

Black smoke is fuel that has started to burn but wasn't completely burnt where as white is fuel that has not been burnt at all. As western says white can also be coolant.

The garage will have removed the EGR (exhaust gas recirculation) from your engine, it's an emission control system and as they said your engine is better without it. EGT is exhaust gas temperature and is measured whilst tuning engines to make sure you don't melt something expensive.

Injectors can be tested but need to be done by an injection specialist i would just get yours reconditioned especially if your planning an overland trip.

here is a link to an article in the tech archive about tuning the 300tdi engine, your engine is constantly over fueling giving the black smoke i'm pretty sure this mod has been carried out on your engine but it has been adjusted too far. I'd suggest turning the smoke screw anticlockwise by small amounts at a time, i believe you will see a marked decrease in the smoke.

HTH

matt

[tweetyduck]

Thanks a million guys. I've just been and collected the vehicle and stopped at an "experts" on the way home. He has confirmed its overfulled and is going to adjust it for me and also show me how to do it.

My feet are blinkin freezing....