Like a swiss watch! Smoothest 617 I have ever seen.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Nice work. I just did this on my '84 but that made me wonder, can the same thing be done to an '85? Its got a lot more vacuum components but can it be simplified to the same setup as an '84? The reason I'm asking is so I can eliminate all the extra junk when I swap engines on my '85s.

__________________
Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

I'm sure that you can do a similar tube removal on the '85, but, it's a bit of a different configuration and does not have the vacuum switches on top of the valve cover. I have not looked carefully at the diagram for the '85 but will help you with it when you get to that point.

ive been trying to do that.. the 85 is a bit more complicated vacuum wise.. i got rid of the EGR line but the ARV(air recirculating valve) has to stay since the 85's dont have an overboost protection solenoind (OBS) i am getting a junk turbo in.. chunked as blade on the turbine side. im hoping to rebuild it and put a bigger turbine in it and i will then eliminate the ARV since the Triple K is out and a garrette is in.

to my knowledge all the vacuum stuff has to stay in the 85's except the EGR.. that was umm stolen on my car..

Thanks. There are two trashcan-like devices that are integrated into the system somehow on the driver's side. They've each got vac lines running to and fro and I was thinking it would be much easier to make it like the '84, which I just did this removal to and thanks again. I'm sure I could get my hands on an overboost protection soleniod if it ment gutting all that other stuff.

__________________
Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

SO IF...

the line to the black box on top of the valve cover is eliminated...

WHAT DOES THE "BLACK BOX" do? What is being shut off by disabling the black box?

IF... the line from the black box to the temperature switch on the thermostat housing is removed.

WHAT does the temp switch do? What are we disabling?

ANY restrictions and concerns by doing this????

I can not find these answers easily after looking online and thru the manual for over an hour so I am replying here... hopefully someone can share some light ASAP because I am working on mine right now.

thanks all.

Do you mean the plastic black cover that goes over the vacuum valves? It serves the purpose of protecting those valves....

IF... the line from the black box to the temperature switch on the thermostat housing is removed.

The temp switch is for turning on the coolant pump once the car is up to temperature in order to circulate coolant, the valve has something to do to that. One can ASSUME that when the rack is advanced and the RPM’s go up, it actuates the valve and lets coolant circulate even if it is not up to temp.

I haven’t had any trouble by disconnecting them.

__________________
1982 300TDT
1991 190D
2022 Metris

well, the title of the post would tend to indicate that you're deleting the EGR, or at least keeping it from functioning as the design intended.

all of the vac tubes and valves underneath the "black box" on the valve cover control when and if a vacuum signal is sent to the EGR valve depending on throttle position. the temp switch on the thermostat housing is the final arbiter as to whether a vacuum signal gets to the EGR valve. the temp switch opens up at a certain temp to pass the vacuum signal, so the EGR doesn't start operating until the engine warms up.

if you just start disconnecting lines, you'll have a vacuum leak. You need to do it like Brian Carlton shows in his post.

the only concern is that if your state requires emission testing, you may not pass. but i think that's a remote possibility.

__________________
cbjukraine
'84 300D

This isn't even close to correct.

There are two switches on the thermostat housing on the 617. One is the electrical cold-engine lockout switch that keeps the climate control system from operating before a certain coolant temp is reached, the other is the mechanical EGR vacuum switch. The EGR doesn't begin working until the engine coolant reaches a certain temp because the vac switch doesn't open until the coolant is warm. I forget the exact temp.

If the engine is running and all is operating properly, coolant is always circulating through at least the block and head, being moved by the water pump. When the engine is hot, the thermostat directs some coolant to the radiator for cooling.

Unless you are referring to the auxiliary coolant pump, but that only works when the heater is on to circulate hot coolant through the heater core at idle.

__________________
cbjukraine
'84 300D

Depending on what year engine you have, the black box can be completely eliminated.
I'm sure which lines to plug off have been discussed.
http://www.peachparts.com/shopforum/diesel-discussion/311007-3-2-vacuum-valves-300d.html
Post #6 in the above link.

__________________
83 SD

84 CD