Jimmy, the vac unit right before the EGR on my car is a thermal unit mounted in the thermostat housing. Air passage between the 2 nipples on top should be shut off until the coolant warms up, then it opens to allow the EGR to start operating by redirecting exhaust crud back into your intake manifold.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Wait a minute. I didn't think that it was condemned yet.

Just my luck, I cleaned out and tested the egr valve on the donor engine for my project from an 84 300TD w 276k- egr holds vacuum perfectly. I got the bright idea to test the one on my 617 w 164k - it leaks, so i tried the one on the blown parts engine i just pulled, it was nfg as well. oh well, egr blocking kits it is then.

hey brian i recall reading you wernt going to turn up the boost on your car untill you repl. the head gasket? whats your pressure now? mines leaking at the usual spot at the center of the rear of the head, my boost pressure is currently 9.5psi and i was going to turn it up to 13-14 if it would let me. I take it I should hold off untill i do the head gasket on it first?

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

The 617 runs about the same. 9 to 9.5 psi. Mine has coolant in the oil, so I'm not about to help that situation along with additional boost right now.

Leaks can only get worse with greater pressures.

Thanks for clearing that up, Pete.
I guess just leaving that thermal unit alone and plugging the EGR should be fine then.

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)