replacing water pump on my old '84 DeVille 4.1 engine

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HT4100 4.1, 4.5, 4.9 Discussion, replacing water pump on my old '84 DeVille 4.1 engine in Cadillac Engine Discussion; I am in process of replacing water pump on my old '84 DeVille 4.1 engine. The crossover housing has a ...
  1. #1
    gsim is offline Cadillac Owners Member
    Automobile(s): 1984 SEDAN DEVILLE
    Join Date
    Mar 2011

    Angryreplacing water pump on my old '84 DeVille 4.1 engine

    I am in process of replacing water pump on my old '84 DeVille 4.1 engine. The crossover housing has a place that fits over the water pump outlet. That requires an O-ring to seal it. Then there is a coupling that comes out of that at a right angle towards the engine head. That is a inch-long steel tube with a lip to fit an O-ring at each end. Those three O-rings also come with a new or reman water pump. I found a bit of what appeared to be permatex soft gasket sealer on the lower O-ring, the one that fits over the water pump discharge. So I suspect that this gasket sealer is something the first owner did to be repair or stop a leak. I am going to put a bit of the permatex soft gasket cement OR the orange high-heat RTV silicone in all three of the O-ring grooves and smear a bit on each 0-ring to boot. I will do this just to be sure that I do not have leaks there as I am reading about on this forum. It is not a hard thing to do at home, but does require loosening the power steering belt via the Air Cond compressor adjust. Plus, the smog pump on driver's side has to be slackened to get that belt off. A power steering pulley removing kit will be needed to pull the pulley off of the power steering pump to access at least one of the two bolts securing the crossover housing. Not nearly as bad a job to do tho as a water pump replacement.

    I am not too keen on adding Bars Leaks or any pelletized supplement to my coolant. I always fear a plugged heater core or a plugged radiator will result in an older car which has never had the radiator rodded or power flushed. I will try to fix the leak if practical before using that stuff for that reason. Bars Leaks is a great product which does what it says.

    I wonder if they put in new O-rings or just re-used the old ones??? It is a pain to make the three new ones fit properly.


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  3. #2
    carnut is offline Cadillac Owners Master
    Automobile(s): 1999 BMW 740 Il. 2005 Jag XK8, 1988 Mercedes Benz 300 SE
    Join Date
    Feb 2003

    Re: replacing water pump on my old '84 DeVille 4.1 engine

    I've always used new. I remove the temp sender in the intake manifold in order to slide the pipe (steel tube) forward to the water pump using a medium sized screw driver. I always use wheel bearing grease on the O rings to allow the tube to slide freely. I insert the tube deep into the intake manifold, mount the pump and crossover then insert the screw driver in the sender hole and pry the tube forward. Make sure the by pass hole in the manifold is clean with no residue as well as the crossover. Any residue will cause failure of the O rings. There should be a thin metal piece that you push down onto the pipe once positioned, that keeps forward tension on the pipe. The sealant was primarily recommended to seal casting pin holes in the early aluminum blocks. If the coolant is changed every two years without fail, the use of the sealant can, as you say, restrict heater cores. Some believe the sealant helps with intake gasket leaks and cylinder liner leaks but my experience has been lack of 2 year coolant changes causes the corrosion of the intake gaskets and liner O rings not the lack of sealant. If the engine is not overheated, the liners dont move.

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