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3.1 MU Smoking

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3.1 MU Smoking

Postby sm00king » Sat Sep 06, 2014 2:08 pm

Hi there,
I have a 95 MU 3.1 Great little car have had it for 3 years 260,000kms been running fine but has just now lost power & stopped .
I restarted it again ( took a bit ) but blew heaps of smoke ( black) on start up then slowly went away drove it home about 2kms and let it idle seemed of no noises or smoke that I could see, was dark at the time though.

next day went for a run to check things after about 3Kms or so same thing this time after I got it started it smoked all the way home with a great loss of power.

Still idles ok with some smoke no noises other than the usual diesel engine noises but will blow big smoke when reved.
It is hard to start must use some throttle and when she fires engine will rattle for a second or two and then settle to an ok idle.

Did easy checks for turbo oil seals, they seem OK ,
Check for blow by into sump , seems ok

So I'm thinking that it could be valve seal/seals have suddenly given up.
Is this possible,
I'm hoping someone has some suggestions before I tear the engine down completely

Thanks for any help

Cheers Steve
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Re: 3.1 MU Smoking

Postby stardog » Sat Sep 06, 2014 5:50 pm

welcome to the club I would say your turbo has had it by the sounds of it.
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Re: 3.1 MU Smoking

Postby sm00king » Sun Sep 07, 2014 8:19 am

stardog wrote:welcome to the club I would say your turbo has had it by the sounds of it.


Thanks Stardog for you advice and welcome

The smoke is Blue not black, sorry about that must have been a typo or poor judgement on my part.

Turbo is fairly new so may not be that I have taken the turbo hose from the turbo and run with out and same thing is happening.

after some more research it would point to valve seals the only thing is, would this happen all of a sudden?
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Re: 3.1 MU Smoking

Postby dani4jb1t » Sun Sep 07, 2014 8:55 am

Hi there

I just recommend you to do a cylinder compression test, because it seems something inside the combustion chamber is worn.....normal reading should be around 450 PSI@200 RPM, with a minimum of 300 PSI....
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Re: 3.1 MU Smoking

Postby stardog » Sun Sep 07, 2014 9:21 am

When was the fuel and air filters last changed also if you had blow by it would indicate rings or valve seals worn but you don't have that I would check the filters and timing.
Could also be injectors as well is it using any oil between oil changes.
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Re: 3.1 MU Smoking

Postby sm00king » Sun Sep 07, 2014 10:21 am

dani4jb1t wrote:Hi there

I just recommend you to do a cylinder compression test, because it seems something inside the combustion chamber is worn.....normal reading should be around 450 PSI@200 RPM, with a minimum of 300 PSI....


Thanks Dani, for that advice , air filter ok checked fuel filter changed ok compression test will do tomorrow

stardog wrote:When was the fuel and air filters last changed also if you had blow by it would indicate rings or valve seals worn but you don't have that I would check the filters and timing.
Could also be injectors as well is it using any oil between oil changes.
.

Again thanks Stardog
Filters ok no sign of blow by,
Oil definitely getting to cylinder/s from where is the question and why suddenly
Also hard to start I have to use some accelerator to get fuel to the cylinders to get it to fire , them rattles for a second or two then settles to an ok idle and seems to run fine except for the smoke , very perplexing
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Re: 3.1 MU Smoking

Postby stardog » Sun Sep 07, 2014 10:49 am

by the sounds of it I think you might be taking the head off it to check the rings and see if there is any scouring in the bores and checking if you have a burnt valves or worn ones there's no water in the oil or oil in the radiator which would point to a head gasket gone.
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Re: 3.1 MU Smoking

Postby sm00king » Sun Sep 07, 2014 11:56 am

Tried to start this morning but no luck ... ( BUGGA) so

Have resolved to attacking the big job of taking the head off .
Does any one have an workshop manual for this engine?
I would much appreciate some / any guidance to attack this job.

I suppose a full head recon is the go here, and may be the fuel pump too, while its exposed?


Many thanks
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Re: 3.1 MU Smoking

Postby stardog » Sun Sep 07, 2014 12:30 pm

look in general Isuzu 4x4 discussion you will see manual down loads for 4jb1 and 4jg2 engines should help you out.
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Re: 3.1 MU Smoking

Postby sm00king » Tue Oct 14, 2014 9:42 pm

Back again I have recon the head new gaskets and had the injectors overhauled , put the whole thing back together and ..... still smoking, BAD now we have white smoke like a smoke screen even at idle
Total baffling apart from frustrating and disappointment really thought this would have fixed the problem.
Engine wont start without a sniff of ether
Thought may be look next at the EGR but not sure what to do next
Thanks for any help
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Re: 3.1 MU Smoking

Postby geeves » Wed Oct 15, 2014 1:42 pm

oil will get into the cylinders via bad oil rings, blowby blowing oil in through the intake, bad turbo seals, cracked bores or leaky head gasket. One other option is oil in the fuel but that is unlikely
Oil in the bores wont cause hard starting in a diesel but low compression will which is why a compression test was suggested. Faulty injectors will cause hard starting and smoke which can be blue.
A bad turbo wont cause hard starting but could cause lack of power
How much oil is in the intake before and after the turbo? What does a compression test show.
What does the smoke smell like?
You are running standard diesel?
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 3.1 MU Smoking

Postby nb422 » Wed Oct 15, 2014 6:35 pm

Also be careful putting ether in a diesel engine, i've been told it can crack pistons if too much is used... apparently something to do with the glowplugs?
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Re: 3.1 MU Smoking

Postby isuzurob » Thu Oct 16, 2014 5:48 pm

sounds like the injector pump timing is out, will cause hard starting and white smoke=unburnt diesel
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Re: 3.1 MU Smoking

Postby Roderunner » Sun Oct 19, 2014 7:08 am

I suspect you may have an air leak in your fuel line, you can try temporarily replacing the fuel return (to tank) line with a length of clear pipe ($5.) and watch for bubbles in the fuel. The other thing that comes to mind is the usual build up of laquer/crap inside the injection pump, which makes the pumps internals (vane pump/pressure control valve) stick, a bottle of diesel injector cleaner does wonders here. The low sulphur fuel we are sold these days doesn't have much lubricity, so internal pump parts can stick open/closed giving the symptoms you describe.
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Re: 3.1 MU Smoking

Postby Roderunner » Sun Oct 19, 2014 6:11 pm

nb422 wrote:Also be careful putting ether in a diesel engine, i've been told it can crack pistons if too much is used... apparently something to do with the glowplugs?

Too true! I have had a piston skirt crack and break off while trying to start an engine with aerostart. The injection pump had an internal build up of laquer/particles that wouldn't allow the pump to supply the normal quantity of fuel required for normal starting/running.
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Re: 3.1 MU Smoking

Postby geeves » Mon Oct 20, 2014 2:39 pm

nice to here that after using half a can trying to start after water in the fuel. Untill the engine warmed a little it wanted to idle at 100rpm Obviously still water in the injectors. 5 years later the rest of the wagon failed and wreckers paid good money
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 3.1 MU Smoking

Postby sm00king » Sat Oct 25, 2014 1:55 pm

geeves wrote:oil will get into the cylinders via bad oil rings, blowby blowing oil in through the intake, bad turbo seals, cracked bores or leaky head gasket. One other option is oil in the fuel but that is unlikely
Oil in the bores wont cause hard starting in a diesel but low compression will which is why a compression test was suggested. Faulty injectors will cause hard starting and smoke which can be blue.
A bad turbo wont cause hard starting but could cause lack of power
How much oil is in the intake before and after the turbo? What does a compression test show.
What does the smoke smell like?
You are running standard diesel?


Turbo recon so shouldn't be that , no oil in intake or outlet.
Smoke smells like diesel and is White
Running standard diesel (changed filter and fuel looks clean
EGC's seem ok , some slight soot nothing drastic
Ok Checked the compression (Cold) 350psi in all cylinders so happy with that.
Tried too start it (no either this time) wont fire but seemed to labour a little as if timing may be out (maybe!) could be battery , sitting for a month.
next step I will take covers off and check timing belt for wear or slip or something.
If this is ok then next will be fuel pump out (ouch) Is there some special procedure for this operation?
Is there any way to test the fuel pump for issues without extracting it?

Thanks for your help
This the best forum,, I have learnt so much so far helped immensely
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Re: 3.1 MU Smoking

Postby Roderunner » Sat Oct 25, 2014 7:15 pm

sm00king wrote:
Smoke smells like diesel and is White

White smoke is usually unburnt diesel especially when it smells like diesel, which points to one (or 2) of three probable problems. 1/ injector timing (unlikely unless the timing belt is loose enough to enable the belt to jump a tooth on the injector pump drive), 2/ injection quantity and pressure- A gummed up pump can give the exact symptoms you describe, a bottle of injection pump cleaner is your friend here, 3/ when you put the head back onto it you could have put the injection lines to the wrong injectors...don't ask me how I know this! :roll: :lol:
The other place to look would be the butterfly valve in the exhaust pipe after the turbo charger (if it has one). If the valve is stuck closed then the excessive backpressure from the exhaust can play havoc with the combustion process.
Tried too start it (no either this time) wont fire but seemed to labour a little as if timing may be out (maybe!) could be battery , sitting for a month.
you really need a fully charged battery for good starts, slow engine cranking speed is not good for starting the engine from cold.
next step I will take covers off and check timing belt for wear or slip or something.
If this is ok then next will be fuel pump out (ouch) Is there some special procedure for this operation?
Is there any way to test the fuel pump for issues without extracting it?
You are better off leaving the pump in at this stage, for testing purposes, as mentioned before a dose of injection pump cleaner (or even better a double dose....read the instructions on the bottle) should clean up the pump internals and allow the pump to operate normally. The pump cleaning juice needs a couple of days to do its thing, along with some engine running time, even if the engine is missing and producing clouds of white smoke.
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Re: 3.1 MU Smoking

Postby sm00king » Sat Oct 25, 2014 9:29 pm

Thanks Roderunner I will check all you have mentioned also timing marks for fuel pump
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Re: 3.1 MU Smoking

Postby gomulletgo » Sun Oct 26, 2014 8:56 pm

I hope someone can clarify below. I was under the impression that the smoke signals of diesels were:

#1 - Black Smoke = Unburnt fuel
#2 - White Smoke = Water in the combustion process
#3 - Blue/Grey Smoke = Oil in the combustion process
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