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  #1  
Old 01-05-2010, 12:13 PM
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Vacuum system freeze up???

We had a cold snap around here lately. It was down to -36c at night and about -25 during the day. It's now -15c. Now the fuel shutoff doesn't work and the brake boost works for a few applications and then is gone. The fuel shutoff problem in the cold happened last year in the cold as well but not the brake problem.

Is this indicative of moisture in the system? Or is this a vacuum problem, ie. a poor pump or leak? What are your experiences those of you in cold environments?
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  #2  
Old 01-05-2010, 09:16 PM
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Hook up a vacuum tester and see if you have decent vacuum or not. You may have a bad pump, a leak that opens when it gets cold, etc...



Quote:
Originally Posted by MotorCityMadman View Post
We had a cold snap around here lately. It was down to -36c at night and about -25 during the day. It's now -15c. Now the fuel shutoff doesn't work and the brake boost works for a few applications and then is gone. The fuel shutoff problem in the cold happened last year in the cold as well but not the brake problem.

Is this indicative of moisture in the system? Or is this a vacuum problem, ie. a poor pump or leak? What are your experiences those of you in cold environments?
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  #3  
Old 01-06-2010, 01:28 AM
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Answer

Quote:
Originally Posted by MotorCityMadman View Post
We had a cold snap around here lately. It was down to -36c at night and about -25 during the day. It's now -15c. Now the fuel shutoff doesn't work and the brake boost works for a few applications and then is gone. The fuel shutoff problem in the cold happened last year in the cold as well but not the brake problem.

Is this indicative of moisture in the system? Or is this a vacuum problem, ie. a poor pump or leak? What are your experiences those of you in cold environments?
Hello Ted

I would guess that the issue is in the engine vacuum pump.
The valves get stiff/hard with age, and extreme cold can cause them to not seal = vacuum loss.


Vacuum Pump Rebuild Thread
http://www.peachparts.com/shopforum/diesel-discussion/229331-vacuum-pump-rebuild-thread.html#post1927867

"Hen's tooth" 1985 300D vacuum filter dark black
http://www.peachparts.com/shopforum/diesel-discussion/163455-hens-tooth-1985-300d-vacuum-filter-dark-black.html#post1265296


Vacuum Pump Repair Kit, For Piston Type, Includes Seals and Valves
MB# 000 586 17 23


Cool name...

FYI:
The MotorCityMadman
Ted Nugent
http://en.wikipedia.org/wiki/Ted_Nugent

Have a great day..
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Last edited by whunter; 01-06-2010 at 01:04 PM.
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  #4  
Old 01-06-2010, 02:47 AM
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I find that vac issues always get worse when it's cold, all the rubber shrinks and get brittle and creates more leaks. So I wouldn't be surprised if you have several leaks when it's that cold, and/or a vac pump thats getting weak. For a temporary fix you could try plugging the supply for door lock and climate control systems in the engine bay and see if that helps the braking and shut off. But testing with the mity vac to see if you pump is pulling enough vac is a good idea too.
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  #5  
Old 01-06-2010, 10:58 AM
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Thanks guys for the assistance. How much vac should I see when testing?

I saw a thread where it talked about needing to make a board jig to take the pump apart. Is that right?

I also read threads that said it was the check valve on top of the pump that was the main cause of failure. Is that an all or nothing type of failure??

Whunter... it's the last name not first....MCM

Have a great day too.
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  #6  
Old 01-06-2010, 11:33 AM
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I get 21 inHG or higher.
Not sure about the check valve, Nuge.
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  #7  
Old 01-06-2010, 11:52 AM
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Answer

Quote:
Originally Posted by MotorCityMadman View Post
Thanks guys for the assistance. How much vac should I see when testing?

I saw a thread where it talked about needing to make a board jig to take the pump apart. Is that right?

I also read threads that said it was the check valve on top of the pump that was the main cause of failure. Is that an all or nothing type of failure??

Whunter... it's the last name not first....MCM

Have a great day too.
It is the temperature related brake boost failure that leads to the vacuum pump diagnosis.


The check valve on top of the pump is generally an all or nothing type failure.
MB# 0049971872

Cool last name.
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  #8  
Old 01-06-2010, 12:24 PM
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Again guys, many thanks. I have just ordered a rebuild kit.

Do I have to build a jig to rebuild it? I tried several of the vac links but I always ended up at a dead end link at the end of the chain of links. Anyone got a link with pics?
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  #9  
Old 01-06-2010, 12:32 PM
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Quote:
Originally Posted by toomany MBZ View Post
I get 21 inHG or higher.
At sea level. Lower at elevation.
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  #10  
Old 01-06-2010, 07:58 PM
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If you can do without it for awhile, I'd do nothing and see if warmer weather solves the problem. Traces of moisture in odd places that turns to ice can lead to a lot of wrong conclusions.
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  #11  
Old 01-06-2010, 08:32 PM
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That would be my preference but as my daughter is driving it to university an hour each way so I am compelled to fix it.

I now have the kit in hand. Can anybody tell me if I have to build a jig for this rebuild?????????????????????????
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Last edited by MotorCityMadman; 01-06-2010 at 10:37 PM.
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  #12  
Old 01-07-2010, 01:19 AM
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Originally Posted by MotorCityMadman View Post
That would be my preference but as my daughter is driving it to university an hour each way so I am compelled to fix it.

I now have the kit in hand. Can anybody tell me if I have to build a jig for this rebuild?????????????????????????
No jig needed.
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  #13  
Old 01-07-2010, 10:22 AM
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Any tips?
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  #14  
Old 01-07-2010, 11:38 AM
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Quote:
Originally Posted by MotorCityMadman View Post
Any tips?
Here's a thread where the OP's engine would not shut off, and how he rebuilt the pump on the vehicle. You've obviously found the procedure in the manual.

Car wont shut off AT ALL!

good luck!
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  #15  
Old 01-07-2010, 08:24 PM
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Thanks for that micalk .

So I tried to take the front cover off the pump while it was still on the engine. The screws were stuck tight so I grabbed them with vice grips to break them loose. That worked all right except for the last one which the head broke off of.

So the plan changed to complete pump removal. To get that off I found it far easier to remove the power steering pump, which I had already had to loosen to remove the belt, instead of draining the coolant and removing the top rad hose. I strongly suggest removing the bottom fastner by the crank sensor first as if you leave it till last the pump spring will fight you on every turn. The broken screw had to be drilled to remove the cover. All new fastners were procured, unfortunately I found that when I got them home they had three different heads (phillips, robertson, and slot) the next guy to take them off will shoot me.

After that everything is obvious except for the piston removal. With the help of someone you can push down on the pump casing with something underneath the rocker arm so as to relieve the tension on the piston nut. The second set of hands are to remove the nut while the first compresses the spring. Installation is the reverse.

Many thanks for all the assistance guys.
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