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Discussion Starter #1
Can anybody tell me about the HT4100 vacuum pump. I have an '84 Coupe de Ville, and the vacuum pump has a bent pulley. It vibrated to the point that it threw the belt and broke the bracket. I can't find one anywhere. Any suggestions? Oh, the car seems to run fine without it. It need it soon, so if possible, you can email me at [email protected]
 

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If I remember correctly, the Vaccum pump has a push-on pulley. Or it may be a simple bolt-on pulley. If it's a push-on, you'll need a special push-on pulley kit for GM vehicles to replace it. You can prob. find a replacement pulley of a junked car with a GM pump. I know in the late 80's, most of GMs vehicles had similar PS pumps, so hopefully Vaccum Pumps were that way too!
No to mention, I have no idea what the function of that pump is! A mechanic was working on my 4100, and said, "Why is there a Vaccum Pump on this engine...it's a gasoline, not diesel!?"
 

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The car needs vacuum to operate several of the emission control devices, provide power for the brake master cylinder power booster, operate the doors in the HVAC system. The HT4100 was a fairly small displacement engine in a larger heavier car. As a result it operates at very low manifold vacuum levels a lot of the time. The vacuum pump is needed to supplement the engine vacuum supply so that everything depending on vacuum will have an adequate amount of vacuum under all conditions.
 

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chevelle said:
The car needs vacuum to operate several of the emission control devices, provide power for the brake master cylinder power booster, operate the doors in the HVAC system. The HT4100 was a fairly small displacement engine in a larger heavier car. As a result it operates at very low manifold vacuum levels a lot of the time. The vacuum pump is needed to supplement the engine vacuum supply so that everything depending on vacuum will have an adequate amount of vacuum under all conditions.
Nice man, didn't know all that!
pfffft...yet another thing tha makes me hate the ol' 4100!:banghead:
 

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That bracket breaks very easy for some reason. I have went through 3 or 4 of them in 10 years. Check with the Cadillac dealer for the bracket (you have nothing to loose), and if they don't carry the bracket any more you will have to go to a pick a part (in that case I would get two or three as spares).

Good luck.
 

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If it's the part I'm thinking of, I may have an extra one lying around. The long tines of a tensioning style bracket broke on a what appeared to be a little pump of some kind that sits on the upper right portion of the engine (as your facing the front of the car) on my 85 Seville some years ago. My mechanic kludged a fix using a big washer. I bought a replacement about a year ago on ebay but never got around to putting it on. Since then I've purchased an 83 seville parts car. So I have one extra. If your interested PM me. I'd be willing to let you have it for the costs of shipping. (provided I can find the durn thing).
 

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Discussion Starter #7
Thanks to everybody who responded. It's been a week and the car runs fine. Probably wouldn't pass emissions. But then I'm diving at an average altitude to 5000 feet. I guess I'll give the problem to my mechanic. He finds parts better than I do. Just thought I'd save a little money. Thanks Again
 
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