Quote:
Originally Posted by Tlaurin
Hello everyone!
So my wife and I decided to get a little project car. I've got a lot of years as a DIY and friend's mechanic so I know my way around a gas engine. Diesel is a whole other story. I'm sure I'll be all over the place and I do have a lot of questions but I'll try to stay somewhat linear.
I'm on mobile so I can't upload images due to size requirements but I will post imgur links if that is allowed; I will delete them if need be.
We scooped up a 1985 California (still got the trap ox) 300D with 177,000 miles. It starts up immediately and runs well. The vacuum was a mess and I am peiceing it back together the best I can. (Didnt even shut off with the key, but i got that!) I've got the transmission shifting better (nothing was connected to the ALDA or the BFS as the elbows were rotted (blue flying saucer???)
So with that, I'll dive right in:
1. There is an inline electric fuel pump scotch-locked under the hood haha. As far as I can tell, there is no pump like that on this vehicle... What would make someone do this? Like what part may have failed? In the past, i have installed one on my old Toyota when my mechanical pump dropped a deuce. Picture link below.
300D https://imgur.com/gallery/MwMG2rI
2. When I inevitabley remove this, as well as replacing a return line that is swollen like all get out, is there a specific priming procedure that needs to be performed? ( this is my first diesel so please bare with me here)
3. I don't think I'm getting any boost pressure.. I believe I hooked the overboost protection valve properly. I want to test this out. Im having trouble understanding the valve.. isot normally open and when too much pressure is induced, does it close and send a signal?? Ive been reading thread after thread but i feel there is so much to do, I dont know where to start! Picture is below (that line that you see going to nothing appears to vent to the cabin so I guess that's nothing)
300D https://imgur.com/gallery/OR5sFQg
Guys, I know this was a book but any and all help you send my way is truly appreciated. My wife and I are excited and love this car and I wanna be able to make it safe and proper for her. Thanks so much!! |
I have not read of a way to test the overboost protection valve.
My personal view:
The exhaust gas pressure and flow turns the tubo which intern compresses the air when it turns fast enough to do that. The increased manifold pressure causes the ALDA to give more Fuel.
When you go say up hill the combustion pressure in the cylinder rises and creates a higher flow and pressure of exhaust gas as explained eventually causes a an even higher manifold pressure in which again the ALDA allows more fuel. Kind of a circular issue.
If you are towing a trailer up a steep hill the combustion pressure in the cylinders is going to shoot up and your exhaust flow and pressure will shoot up and since you are sort of lugging the engine you don't want the extra manifold pressure causing more fuel to be delivered. What you need to do is down shift. Anyway in that situation the overboost protection valve cuts off/reduces the manifold pressure/signal to the ALDA and keeps it allowing more fuel.
While the wastegate is supposed to open and bypass the turbo and dump off some exhaust gasses to keep the manifold pressure in check apparently Mercedes felt the need for a back up or perhaps there is some odd situation where the wastegate cannot bypass enough exhaust gas to protect the Engine from being over fueled.
In normal driving you could actually just run a hose straight to the ALDA as some in the past have done and you will have no safety issues. If it seems like you are lugging the Engine switch down to a lower gear if the Transmission does not do that for you.
If you tow a trailer having the overboost pressure switch connected would be a good idea.