still overheating

[fla.viper]

took the virage for a test run with the new low water pickup lower unit, and dident even make it out of the manate zone. i never had any overheat problems with the old lowerunit. i even put my old waterpump assembley on it. does any body make a high performance waterpump for a XR4? water presuer still 2-7 psi. any ideas?
tx mike

[idvette]

If your pump and housing are in good shape, the problem's somewhere else. Since you just replaced the lower, I'd assume the problem's not in the block, but you know what assuming can lead to... I'd be pulling the lower back off and making sure all water passages are clear, in the lower and in the block, and make sure the transfer tube (is that what it's called? The one between the lower and the block) Is fitting properly.

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[varmint1]

You should be running more pressure at idling, Im running bout 10 idling and all depends on how hard I'm running it 20 to 30. I had an overheating problem then I burnt a piston, come to find out the head gaskets were bad, compression was getting into the water jacket ( compression was more than the incoming water pressure ). If I was you I would replace everything from the water pump base to the grommet that slides down the driveshaft after the water pump housing is on, new impeller, gaskets o- rings

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[RussF]

put the other unit on and see

[Fastride]

Fl.Viper I'm having the same problem with the 300 Mariner I just put on. I changed my impeller and took it out today and only had 2 or 3 pounds pressure at idle. I already pulled mine back apart to change all the gaskets, O-rings, and the shaft seal.

[fla.viper]

i have to assume the problem is in the lowerunit. i hooked a garden hose directly to the water intake fitting on the water pump to flush the salt water from the motor. i expected to see better pressuer, but no. still 2-5 psi. the water hose puts out more than that. my next plan is to completely replace every thing that has to do with the waterpump. should i get one from mercury dealer, or is there another manufactuer produceing a better unit? tx mike

[RussF]

I use Merc stuff for that

[transomstand]

Replace EVERYTHING with new Merc stuff first.

[fla.viper]

think i may have found the problem. the rubber seal in the waterpump, where the pickup tube goes in is completely missing. i found this by compareing each componit of my old unit, and the new deffective one. im on my lunck break, so i wont reasembl and test till after 6:00, let u know what hapens.
mike

[transomstand]

think i may have found the problem. the rubber seal in the waterpump,

They never listen to me

Change the base too. Make sure the rubber seal is in the top of the water pump housing. Guy probably just put an impeller in it, which is a waste of time.