1982 300D Turbo questions and comments - Page 3 - PeachParts Mercedes-Benz Forum

#31 07-15-2006, 10:55 PM

Quote:

Originally Posted by Brian Carlton

Could be a matter of semantics.

He's correct in the fact that the absolute pressure in the cylinder must be less than atmospheric pressure........so.......effectively there is a small vacuum on the intake stroke.

But, clearly the vacuum is nowhere near the typical gasser which must struggle to draw air past a throttle plate that is usually 60% closed.

Sure, that makes sense, but I think he was trying to say that the "vacuum" in the inlet tube (between the cone filter and the turbo) was going to pull a crankcase vacuum. Obviously the pressure in the inlet tube is less than the crankcase, but the crankcase is still going to be slightly positive and the inlet tube is only going to be sightly negative. Maybe I misunderstood?

resago · #32 07-16-2006, 01:49 PM

yup, semantics.

when the turbo spools up, there is significant vaccum between the filter and the turbo inlet.

but before it spools up, there is a little vacuum from the pistons on the intake stroke

anyway, does anyone have a diagram or picture of where the modulator is on the tranny?

Brian Carlton · #33 07-16-2006, 01:55 PM

Quote:

Originally Posted by resago

when the turbo spools up, there is significant vaccum between the filter and the turbo inlet.

Here is where we definitely disagree.

Any vacuum at that location would imply a restriction in the air filter. I'll grant you that it might restrict on the order of 2" or so. But, to state "significant vacuum", you'll need to put up some data.

I'd seriously doubt that the stock air filter would be more restrictive than 2" or the design is seriously flawed.

resago · #34 07-16-2006, 01:59 PM

I think my timing chain guide broke.

my engine is making a hell of a racket

, but power has not been affected.

above 2500rpm, the noise all but goes away, I'm guessing because of centrifical force, the chain takes up the slack.

Any ideas?

Like I said, power has not been affected. and there is no smoke in the exhaust

oil pressure is 3 bar unless idle at 2bar. Running temp is 80C.

this is 225K mile engine, and obviously has had work done before because the vacuum system is wrong and there is sillicon around the valve cover.

resago · #35 07-16-2006, 02:08 PM

Quote:

Originally Posted by Brian Carlton

Here is where we definitely disagree.

Any vacuum at that location would imply a restriction in the air filter. I'll grant you that it might restrict on the order of 2" or so. But, to state "significant vacuum", you'll need to put up some data.

I'd seriously doubt that the stock air filter would be more restrictive than 2" or the design is seriously flawed.

tell ya what, I'l put a vacuum gauge on a stock inlet and my inlet and get the numbers.- After I fix the engine

#36 07-17-2006, 03:30 AM

Quote:

Originally Posted by resago

I think my timing chain guide broke.

my engine is making a hell of a racket

, but power has not been affected.

above 2500rpm, the noise all but goes away, I'm guessing because of centrifical force, the chain takes up the slack.

Any ideas?

Can you tell were the sound is coming from? Make sure it's not the vacuum pump failing before you start digging into the chain guide. Either way, I wouldn't rev it to 2500 rpm (or drive it) until you find out what's broken.

The power and lack of smoke would indicate that the cam is still timed correctly (didn't jump a tooth), but it still could be a chain guide. Sounds like it's time to take off the valve cover and have a look around.

resago · #37 07-17-2006, 03:16 PM

valve cover off - nothing obvious.

bumped it over and noticed a bump-bump-bump in the lower end.

so best case is loose rod cap.

worst case - replace:
crank, rod, bearings, piston, sleeves, rings, etc. etc.

ConnClark · #38 07-17-2006, 04:14 PM

Ummm.... this sounds very familair to me. It sounds like the symptoms my 79 had when the crank cracked. A loud clacking noise that goes away at higher rpm.

resago · #39 07-17-2006, 11:13 PM

ah crap, don't say that

resago · #40 07-21-2006, 11:17 AM

what would you do?

1)Get a 225,000 mile engine fixed
a)only replace damaged parts. $350 + labor
b)replace crank,rods,pistons with lower mile parts $750 + labor
c)replace crank,rods,pistons with new parts ($EXPENSIVE$)

2)Find a wrecked car with a good engine - price?$$$

3)Just find another 300D turbo for around $2000

I am so bummed, I was really enjoying fixing this thing up.

ConnClark · #41 07-21-2006, 11:53 AM

I feel for you.

Since you enjoy fixing it up, I would say option 1 and 2 would be good choices. With option 2 you might want to buy the whole hulk for spares.

Look at it this way after you bring the car back from the brink you will have made it a labor of love and bonded with it. You will then take excellent care of it.

resago · #42 07-27-2006, 06:28 PM

I'm buying an engine from another forum member. I should have it in my hands by the 3rd.

Is there a tutorial of an engine swap online?
I am familiar with a wrench, but every car has its secrets.

85chedeng300D · #43 07-27-2006, 09:12 PM

Quote:

Originally Posted by resago

I'm buying an engine from another forum member. I should have it in my hands by the 3rd.

Is there a tutorial of an engine swap online?
I am familiar with a wrench, but every car has its secrets.

No need for a tutorial, a gearhead's point of view can figure it all out.

resago · #44 07-27-2006, 09:30 PM

funny.thanks for the response.

I was talking about tips on removing the accessories without having to remove all the attached hoses. IE A/C, steering pump, etc..

am I going to have to remove the radiator to get the engine/tranny out?

what are the gotcha's on this car?