High water pressure & low water temp

[njj502]

Guys, this winter I put my ProMax back on a 2pc plate, put the poppit back & the t-stats. When I first fired it up in the water my PSI was fine & no temp. I expected this as the water here was only 42*. When I got the chance to actually run it the water was probably 45*. Fired up backed off the trailer and everything was good. Idled around a bit and the stats opened about 145*. Pressure never changed... took off and wham, buried the water pressure gauge and the temp gauge fell way below 100*.....

I'm lost.... How can high pressure also create low temp? Also note that I changed the water pump cover and feed tube from 3/4" to 1/2"..... I think I got all the right gaskets...... are any of the adapter gaskets from the mid up to the powerhead different between a 200 2.5 and a ProMax 225?

[transomstand]

Stuck poppit or dump hole restricted.

[njj502]

Dump hole in the plate, Pete?

[transomstand]

Dump hole in the plate, Pete?

Yep, or gasket material blocking it, etc. As rpm rises, you should see a pronounced drop in pressure at about 1800-2000 rpm. If that's not happening, the poppet isn't working.

[transomstand]

Also need to add. Be VERY careful in this testing process, running at 100° or less is getting you into cold sieze territory.

[njj502]

I feared it all last year but amazingly enough it stuck together..... My guess is b/c the bores have been honed and still has STD size pistons in it..... FYI I was running restrictors, blocked poppet & a 1pc plate last year.... never broke 110* ish....

Thanks Pete.

[Go Time]

My promax with 2 pc adapter, poppet and T stats run around 15#- 20# max pressure. and temperature varied with injection temp..... I ran my other promax with 1 pc plate with restrictors in the drain holes (19/64"), no T stats (1/8 hole in washer), Poppet is N/A and diverters in the block....water pressure will max at 30# and temp was at 115 degrees with 60 degree water inlet temps. Hope this helps.

[texasvector]

My promax with 2 pc adapter, poppet and T stats run around 15#- 20# max pressure. and temperature varied with injection temp..... I ran my other promax with 1 pc plate with restrictors in the drain holes (19/64"), no T stats (1/8 hole in washer), Poppet is N/A and diverters in the block....water pressure will max at 30# and temp was at 115 degrees with 60 degree water inlet temps. Hope this helps.

what are the correct t stats? temps? 140-145? my promax has been running 10-14psi WOT but the gauge never came off bottom. thought it was gauge/sender but found it was t stats stuck open. i want to replace with correct ones.

[njj502]

143* is the correct stat I believe.

Thanks for all the thoughts guys..... Once I get a chance, and it quits raining, I'll go pull the poppit and see if I got crap in it... I MAY be missing a grommet/seal there.... not sure...

Nick

[njj502]

Pulled the t-stats and poppit out yesterday. Everything seems ok. Still have 8-11 psi at idle. At about 2K it drops but then comes right back up. No effect on pressure when tstats open. Guess I need to pull the PH and look for trash in the adapter plate.

[3springers26]

i have a 98 225 pro max 3-5 @ idle. 15 @wot BONE STK.. IF the lower water pump housing has been changed & a mercruiser one installed.. you'll have higher water pres & over cooling issues.. the bleed off hole DIA is diffrent from outboard to M/C.. I have run into this before as the alpha 1 gearcase shares the same shape water pump as a 2.5L outboard but the bleed off holes are diffrent

[njj502]

I'll look at that! That makes more sense as I've got no idea how I could have plugged any of the dumps.... that and over cooling and over pressure doesn't make sense..... to me that means I've got WAAAYYYY too much water volume to the engine and I'm still dumping it somewhere....

Thanks for the tip!

[Go Time]

NJJ502, when you had the poppet out did you check the discharge port where the water passing the valve goes down into the exhaust hosusing to make sure there wasn't anything in there. All 2.5L 225s, 200s and 150s I've had always had 2-5 LBs max at Idle and 12 to 18 at WOT when in stock configuration (T stats w/ poppet). Junk in the adapter might reduce water supply but I doubt it would increase it since the poppet is what regulates water pressure and if the discharge hole is clear, theres nothing to restrict flow (increase pressure) downstream that I can think of.

[specboatops]

Nic, did it do this at all last season ?

[njj502]

So I didn't get a wire or anything to check it.... Looks clean as can be to the eye but I know that don't mean much. My thought to 3 springer's comment is that possibly since I've changed pump housings maybe I'm pumping so much water now that my poppit cant dump it all.... hence high pressure and cold temps...... dumping the excess water but just not enough.... Once I bring the engine off idle I see the pressure dip once the poppit opens but then it just keeps climbing....

NJJ502, when you had the poppet out did you check the discharge port where the water passing the valve goes down into the exhaust hosusing to make sure there wasn't anything in there. All 2.5L 225s, 200s and 150s I've had always had 2-5 LBs max at Idle and 12 to 18 at WOT when in stock configuration (T stats w/ poppet). Junk in the adapter might reduce water supply but I doubt it would increase it since the poppet is what regulates water pressure and if the discharge hole is clear, theres nothing to restrict flow (increase pressure) downstream that I can think of.

Chris, last year it was on a 1 pc plate, no poppit or T-stats. I've changed it all over to stock so that I can build some temp & pressure.... This has turned into a real bastard child and a total cluster F. I'll get it ironed out tho....

Nic, did it do this at all last season ?