New 603.972 not perfect yet - need help

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arvalente
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Location: Portugal

Dear all,

it seems my endeavor is not finished.

The new engine rund perfect, is a March95 engine, 190k, good oil pressure, excellent start.

With 80ºc thermostat, engine is always around 80ºc, full gas 90ºc.

After a good ride and really hot I can open the expansion reservoir, not even a small puff, perfect.

But.....

I've no real power, climbing from low revs it makes sometimes a strange noise, like a screech, continuous an disappears, a not real power, when uphill engine has dificulty to go over 2000 revs.

It On the road it seems a diesel without turbo, or with a very low pressure it does not builds enough pressure.seems like the turbo as a leak... when it starts building pressure it leaks...

On flat areas, I can get to 110-120km/h with difficulty.

I've dificulty to kickdown and gear changes are more brutal.

I've checked the vacuum lines and turbo was rebuilt on April.

With the car stopped and we accelerate it seems to rev normally, no smoke... seems perfect.

Any ideas?

BR

Antonio

 

 

G-Restorations
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Re: New 603.972 not perfect yet - need help
Check the boost pressure, the ALDA unit may need to be adjusted. The Alda isn't the square diaphragm unit on top of the pump if its out of adjustment your motor will be starved of fuel, You can take it off completely and try a run, you should get black smoke before the turbo spools up Hope this helps Gordon G- restorations
JASONGDS
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Re: New 603.972 not perfect yet - need help

I had a Toyota that did the same thing, until the pump was turned up a bit, and then a different vehicle,

arvalente
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Re: New 603.972 not perfect yet - need help

Thanx, I tried that, even changed from the previous engine, basically the same.

Tomorrow I go to MB dealer, that's where the turbo was changed with a rebuild one (I kow where they source the repair - BOSCH center).

I really have a bad feeeling, it seems like a metal noise... like when turbo is in full load, some metal contact.

Sometimes it makes the noise, other times it doesn't, it start's screaming around 2000 rev's.

How we check the turbo boost? any ideas/pics to place the sensor?

BR

Antonio

Pistonhead
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Re: New 603.972 not perfect yet - need help

Hello Antonio,

I do not know if you have provided any background information or not like vehicle mileage etc. But expect turbo wear in high mileage vehicles. To check for this is remove the rubber hose or piping just on the turbo outlet exposeing the turbine. 

Hold firmly with thumb and finger the center nut and lift up and down in a 12 and 6 O'clock position. Obviously ther would be a tinest movement but if it is excessive it will move a lot; if so, its worn and get a second opinion from the turbo specialist.

Do not tell them you know it has excessive play but ask them to check and report on it and ask also what the tolerence should be and what they have recorded.

To test turbo boost you will need a boost gauage and this will need to be connected to a suitable point on the inlet tract, a point after the turbo and inlet manifold. Once connected start the engine and check boost you get against engine revs. This is best tested under load, i.e. whilst driving. 

Another contributor has provide this test, check your other thread.

arvalente
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Re: New 603.972 not perfect yet - need help

Today I went to MB dealer and we tested turbo, 3rd gear full power/load,

0.7-0.8 bar. it seems ok, turbo was rebuilt on April, so it should be ok.

I've found some cracks on the plastic U tube that comes from filer and into turbine, I've taped and glued to see if the scream I hear was resulting from this cracked tube.

Still have the scream, so tomorrow I'll take out the U plastic tube and see if still have the scream.

The car stills lacks power, like if the pump does not deliver enough fuel.

I've changed alda valve, still the same.

So, I'm a bit full of all this nonsense and I'm considering to change the injection pump from the old engine to this one.

It is interesting as MB kown for being a Diesel specialist has built such underpower and unreliable model.

Generally all G models are underpower, too much fuel comsumption and it's incredible like toyota has produced a 4.2 liter for the HDJ80 at same time.

BR

Antonio

tony.bruegger
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Re: New 603.972 not perfect yet - need help

.8 bar is factory original output...try with air cleaner /intake pipe off...350 running well is sweet and powerful...sounds like short of fuel...only the best Bosch specialist can set these pumps to optimum....Axel and I have only found one competant and interested agent in a 100 mile radius of Bristol

Maybe a little more advance until you hear that classic diesel knock/crackle sound

RE: Toyota - one of the world greats in certain guises 4.2 legendary long life old school engine ,can be juicy when worked hard.

arvalente
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Re: New 603.972 not perfect yet - need help

I've booked an apointment in september on Bosch diesel specialist to check injectors and pump.

Some topics still unsolved after I change the engine:

Why I've now a much more hard gear change?

Might be I have a bad vacuum line?

Today I changed oil and still the same, might be the "new" engine is producing more/less vacuum?

In my 300CE24V we could adjust the vaccum assistance in the gearbox but on the G we do not find the same tuning possibility?

I still have the "scream" coming from the turbo side, one in a while on heavy load.

Some things to solve.

BR

Antonio