2,5efi psi

blackbeard · 27-06-2010, 01:50 AM

hi all, can someone tell me what water psi i should be getting from my merc 2,5efi, shes a 1997,
many thanks
chris

TWIN RIG · 27-06-2010, 08:42 AM

I've had a few efi's and had water pressure from 8psi upto 15 psi . If you run the engine on the hose don't expect to see much if any water pressure .

blackbeard · 27-06-2010, 09:02 AM

cool,im getting bout 10psi at wot, is that ok

Jay Smith · 29-06-2010, 11:29 PM

IMO 10 PSI at WOT is a bit low. Make sure your gauge is accurate as well as the water intake on your gear case is low enough to feed the water pump with enough supply to cool the motor and supply 15 PSI at WOT. Anything under that 15 PSI at WOT I would bee looking for a supply issue..

Good luck,
Jay

Hydrostream · 30-06-2010, 11:09 AM

I peg a 30 psi guage at WOT, about 5 psi at idle

Jay Smith · 01-07-2010, 07:14 PM

Most Mercury outboards I find that have 30 lbs or more water pressure at WOT have either have an inaccurate gauge or a restriction of the spent water leaving the block. The only way a water flow will show excessive pressure is with a restriction (or the natural path of the water though the block) anything over the amount thats normal going through the system points to a added restriction, such as clogged spent water dumps in the tuner adapter, pebbles or aquatic material in the divider plate etc...

Always remember :High pressure does NOT mean a high amount of water flow it means the pump is dead heading more than "norma" restriction path. If I had any V-6 Merc. the gauge was correct and I was showing 30 PSI at WOT I'd be looking for a restriction my bet is your not getting the AMOUNT of cooling media that your engine is needing.....

Just my .02
Jay

Cheers,
Jay

Hydrostream · 01-07-2010, 08:05 PM

Thanks for the heads up Jay, I thought it strange myself and pulled the powerhead to check the adapter plate.
Everything looks fine, thought it might have been exhaust pressure leaking into the plate also but no signs of that either. Replaced gasket.
No stats and poppit dump is clear.

It's a sportmaster with large water tube, so I just put it down to the extra volume through the system at wot!
It's certainly a lot better than the 10/12psi we got when we ran the CLE.
Should I check again for blockages? or look at relieving pressure?

Thanks, Alan

Burty · 01-07-2010, 10:12 PM

if you haven't got any stats have you got the restrictors in the heads?

Jay Smith · 01-07-2010, 11:20 PM

Alan,
Might try checking the cross over passages at the divider plate ( 4 places ) to the sides of the bores. As well as the 3/8" dumps on the tuner adapter. I find some folks like to get creative by restricting those 2 dumps to raise pressure and it will indeed raise the pressure BUT starve the motor for cooling media flow... I'd MUCH rater have lower pressure and more volume that the other way around..

Cheers,
Jay

HI ROB !

Jay

Hydrostream · 02-07-2010, 01:40 AM

Quote:

Originally Posted by Burty

if you haven't got any stats have you got the restrictors in the heads?

Burty, to be honest I dont know, never had the covers off! Motor is prety much the way it came from hutchy.

Jay, could be! Motor is a steel sleeve so might have been trying to build heat.