MK SD33T questions

[otis05]

hello guys,

This si my first question here. been looking heaps and u seem to be the knowledge base of nissans.

I have a 1984 MK LWB SD33T. Recently fitted boost guage and checked boost during runs. Stopped at 6psi. Removed hose from wastegate controller and now go up to 9psi, maybe more but i don't push the old girl - done 310,000km. I did notice a fair bit of oil in the intake manifold and some oil running out of the wastgate tube when I removed it and blocked it.

Is this typical and/or how can i block or divert the pipe from rocker cover? There is also a pipe from crancase on side that feeds rocker cover. Same deal it seems to run fair bit pressue in to rocker. Is this all OK?

ta

[spannercrab]

These hoses are essentially your blow by return hoses - some old diesels have them straight out into the atmosphere.

Basically the purpose of the hose is to scavenge the gases that get past the pistons and put them through the engine for "processing" ... so it doesn't blow crap out into the air.

The pressure is actually coming *from* the rocker cover due to blowby from the crank - not to it.

Only if you were running a hose from the compressor discharge side of the turbo to the rocker cover would that be a problem.

[DR Frankenstine]

If you have disabled the waste gate and only getting 9lb of boost you have a problem. A little oil is ok in the manifold but I have never seen oil in the waste gate actuator tube. Mine would boost up to 25 lb if I adjusted the boost controller up so only getting 9 lb with the waste gate fully shut ????

[otis05]

Hmmm. Thanks for the crankcase info. It certainly sounds and looks right.

The old girl may have a worn engine as I can only get the revs up to 2500 at any time full load or not. I have suspected worn rings but it doesn't blow any smoke, maybe a touch off blue on start up as usual, and some black when cold. But when running hot on light load she doesn't blow any. Put down my foot in the sand, etc, and she loves to smoke black, under load.

Maybe check injetcors / pump for service? Check turbo for seal? Waste gate leaking or just old? I don't feel like spending big dollars as she is reliable and never faults.

[zen]

check the obvious first..air filter.fuel filter.injectors. pump.

[spannercrab]

Agreed - a failure to achieve revs is more likely to be a fuel fault that a turbo fault. You could theoretcally remove the turbo altogether and still achieve full revolutions.

I would discount the turbo at this stage and work on getting it to rev.

Fuel & air filter, fuel gauze etc ... possibly a governor / aneroid?

Too much black smoke is bad as it indicated you may have a restriction in the intake / exhaust ...

Considering you can't achieve more than 9psi, quite probably fueling ...

[Patchy]

just a quick one. i just brought an MQ all is good 185,000km's on the clock but cold start up she has some trouble. but once warm no smoke at all even under load hard acel from standing, where you might expect it. just wondering what experiances some people have had previously. my first thought was glow plugs, but if that was the case it wouldnt start at all. My second thought was perhaps its not fueling enough at cold start and causing it to stall. i have to put the acel down slightly to keep the revs up at cold start. in saying this where should the sd33t engines idle it starts fine once warm.

cheers Aaron

[zen]

glow plugs..maybe some are dead so only firing properly on some??

cold start on injector pump not working properly(if fitted)?

[spannercrab]

This is pretty standard behaviour from an older diesel ...

As zen point out - could possibly be glow plugs, check by removing the commoning bar and applying current individually - there should be a noticeable spark when applying current ...

Or, it could just be low compression due to glazed cylinders / worn rings - no big deal ... as they heat up, the compression improves and away you go ...

[Patchy]

cold start on injector pump not working properly(if fitted)?

do these have a cold start on the pump do they? a good work shop manual would be great' gregories tend to be fairly light on the info and would love to get my hands on a genuine nissan manual

[Patchy]

As zen point out - could possibly be glow plugs, check by removing the commoning bar and applying current individually - there should be a noticeable spark when applying current ...

wont this just keep blowing the glow plug circut fuse?

[spannercrab]

ummm ... nope ...

By "apply current individually" I mean:

1. Remove the commoning bar from the top of the plugs

2. Get a stout piece of wire, and connect one end to the + battery terminal, then touch the other end to the top of each glow plug in series.

No spark = dead glow plug.

You can also pull the plugs and check them inidivitually with a meter but you risk:

1. Breaking the plugs off (does happen & not pleasant to deal with).

2. A false reading (very possible - just because you get a reading, doesn't mean it's capable of carrying current).

[DR Frankenstine]

Glow plugs dont do jack after the thing is up and running!!! If it won't rev past 2500 rpm it deffinatelly needs more fuel and thats why its not boosting up. Reconnect your waste gate tube and give it 1/2 turn on the fuel adjusting screw on the pump. If the max revs get less you turned it the wrong way so then give it 1 turn the other way. If this improves things get it to someone who knows what they are doing to tune it properly.

I suspect you have been playing with things to get it going better and have just managed to stuff it up!!! SORRY IF IM WRONG ABOUT THAT ONE

[otis05]

Ok. I know my way around the motor quite reasonably buit not sure about the fuel adjusting screw. I didn't think we had much on the adjustment side of things with these inline injector pumps, except max fuel stop and idle.

I am leaning to getting it tuned, but if you send me in the right direction to try the fuel adjusting stop, that will put me in the right direction. good motor just needs a little tlc.

[Patchy]

what is the idle ment to be on these engines mine is under 300rmp when cold when warm its about 400rpm whats the 2 litle dots on the tacho at about 600/700rpm? is that where idle should be. also if this is wrong where is the idle adjust scew.
ps. are the gregories manuals any good?

[Patchy]

ok so i just checked the owners manual and it should be 600rpm so now where is the idle adjustment on the pump for these???

[DR Frankenstine]

Ok. I know my way around the motor quite reasonably buit not sure about the fuel adjusting screw. I didn't think we had much on the adjustment side of things with these inline injector pumps, except max fuel stop and idle.

I am leaning to getting it tuned, but if you send me in the right direction to try the fuel adjusting stop, that will put me in the right direction. good motor just needs a little tlc.

Its on the side of the injection pump as you look at it. It moves a 1/2 moon cam type thingy. The Idle adjuster is on top of the pump.

[Patchy]

i had a quick look earlier today is the idle screw the 10mm nut with the cut in the head for a flat head screw driver? i will have a better look tomoz

[herks]

If you have not already checked, slip out the primary fuel filter from the banjo coupling at the bottom of the lift pump. Bet you it will be full of crap, restricts the fuel flow and as a result wont rev and thus lacks power. if you find it blocked then also change your fuel filter cartridge as well because it will be in the same state. I had same problem 6 months ago and was an easy fix.