HT4100 4.1, 4.5, 4.9 Discussion, Valves...4100 in Cadillac Engine Discussion; Hello, I have been having a problem on my Deville with a rough idle from time to time, and skipping ...
- 12-22-09 02:04 PM #1Cadillac Owners Fanatic
- Automobile(s): 1984 Coupe Deville, 1989 Brougham, 1984 Mercury Cougar,
- Join Date
- Sep 2009
- Atlanta, Georgia
I have been having a problem on my Deville with a rough idle from time to time, and skipping during driving. I take it this place that specializes in Cadillacs and they claim "the valves are sticking and you need a $2000 valve job"......Anyone have any input on this?? The engine is the HT 4100 and has 52k miles on it, it was driven off and on and when I took possession of it, I noticed the rough idling a couple years ago. It seems to accelerate fine if thats any help.
- 12-22-09 02:07 PM #2
A little more information, I have done a FULL tune up, tried STP in the gas tank as well. The shop that diagnosed the valves say they did a cleaning of them with some chemical, but that did not work at all either.
- 12-22-09 11:48 PM #3Cadillac Owners Connoisseur
- Automobile(s): Cadillac 78 Seville, 78 Coupe de Ville, 92 Sedan de Ville
- Join Date
- Feb 2007
A good shop would do a compression test if they thought there were bad valves. I would say it takes a darn good mechanic to get these heads off and back on again without problems and I wouldn't risk it. When the 4100 dies an early death like most do, it is time to replace it with something else. When was the last tune up on this car? Isn't there a service engine light and a digital information center on those cars so you can read codes?
- 12-23-09 11:05 AM #4
- 12-24-09 12:00 AM #5
If you intend to keep the car: you should buy the Cadillac Factory Service Manual. Should be some on ebay.
- 12-24-09 12:39 PM #6
you have the RWD 4.1 so all bets are off
- 01-01-10 07:36 PM #7Cadillac Owners Enthusiast
- Automobile(s): '85 Fleetwood FWD
- Join Date
- Mar 2009
I use Marvel Mystery Oil for sticky valves, and it works. It's worth a few bucks to try some, if in fact the problem is sticky valves. A pint in of it in the engine oil is what I would use.
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