Water pressure

This topic has 25 replies, 11 voices, and was last updated 14 years, 2 months ago by Weisinger03.

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March 3, 2008 at 8:42 pm #322766

DPT2005
Participant

5# at WOT sounds a little dangerous to me. I think 10-12 is the minimum for WOT. Others will give you a better explanation im sure.Kent Charles 2002 Pantera Classic & 200 Yamaha VMax

March 3, 2008 at 8:58 pm #322784

Bass Cat Boats
Keymaster

5# at WOT is too low. It takes some pressure to keep water all the way up to the top of the block. Lower WP is the quickest way to cook #1 piston/cylinder since they are the highest point on the block. Either (a) your motor is too high or (b) you need low water pickups. If you have an opti with the low water pickups on the front of the gearcase, see if they are full of crud, which will plug em up. Usually, unless you are into choppers/cleavers, by the time you are down to 5# of WP, your prop slip is bad enough that you have already started to lower the motor on the jackplate anyway… If your prop is not slipping (compute theoretical boat speed and compare to actual GPS speed to see the difference, if it is 10% or less you are doing well and that height is OK from a slip point of view) then going to a lower-water-pickup location will solve the pressure problem, assuming you are sure that the impeller is in good condition.2008 Pantera Classic2014 Mercury Pro XS 200

March 3, 2008 at 9:59 pm #322802

Bass Cat Boats
Keymaster

It would be too high, as this engine would have the gear case nose pickups on it we think. Or it could be a faulty water pump. Water pressure is fine at idle with 5 pounds. Does it have nose pick ups? BCB

March 4, 2008 at 1:18 am #322821

LashCat
Participant

Nose pick ups? Sorry to be so uninformed…. I just recognize the problem or potential for a problem and need advise on how to correct it. Last edited by LashCat on March 4th, 2008, 2:45 am, edited 1 time in total.

March 4, 2008 at 3:12 am #322840

PhilAddison
Participant

nose pick ups are located at the end of gear case. There will be 4 fairly large holes at the end of the bullet shaped nose cone. Which engine do you have? I dont think the 2.5 Mercury 200s have the nose pick ups. The Optimax 200s and the EFI 3.0 200s do. Do you have a jack plate? If you have a jack plate and the water pressure gauge is working correctly then you need to lower the engine. If you dont have a jack plate, then its almost be impossible for the engine to be too high and would lead to a faulty gauge. Pee hole water doesnt mean anything. Has your engine overheated when you were running 5 psig?

March 4, 2008 at 11:48 am #322859

LashCat
Participant

2.5L 200hp EFI 6″ Slidmaster JP with engine at 3.75″ below the pad. Never overheated running at any psi. How would I know if its a faulty gauge? Is it possible that it could give accurate readings at some levels of trim and inaccurate readings at full trim? Maybe I just need to trust the gauge and not over trim. Seems I wouldnt be getting the full benefit of the engine though if I cant “give it all shes got” when I want to.

March 4, 2008 at 12:14 pm #322876

Bass Cat Boats
Keymaster

LashCat, I have a few questions. How long have you had the boat? Did these low readings just begin or have they always been low? Guys, I might be wrong (often am) but I dont think the 2.5 200s had the nose pick ups. If it does, then it sounds as though they are clogged. If it doesnt, it sounds as if the engine is too high. It could be a faulty pump or clogged screens but if so, why such good pressure at idle? Since the pressure gauge is consistently reading low at trim and OK with down trim, the gauge seems to be working correctly. Either way LashCat, you need to get your pressure up over 5 at WOT or Mercury will be glad to sell you another engine. As BCB stated, the 5 at idle is fine but not at WOT.

March 4, 2008 at 3:37 pm #322895

Bass Cat Boats
Keymaster

Those later 2.5 engines had nose pick ups.

March 9, 2008 at 12:46 am #438372

Basstar
Participant

If that is 10 psi running at top end, then be sure to get this corrected or discover if it is a gauge or reading problem as 10 psi is low for top end. This could be a bad water pump, restricted flow due to debris, etc. As for water in the hull, assuming no water had gotten in through the cover or while sitting or traveling, more than likely it is a loose hose or fitting such as where a hose attaches to a pump.

March 9, 2008 at 12:48 am #438373

Bass Cat Boats
Keymaster

Water pressure should be above 15 psig. in a Cat at WOT. It will be lower and lower speeds. Could be time to change the water pump impeller. You might want to take to a mechanic. Better safe than sorry. As far as water in the boat it could be from backwash that you didnt know occurred. Good luck finding your problems.

March 9, 2008 at 1:13 am #438374

Bass Cat Boats
Keymaster

Pump housings can break in colder weather when frozen. If your boat took on more water than you though it should, then keep an eye on it next time you launch, and check the internal bilge area for leaks in the sump. BCB

March 9, 2008 at 9:13 pm #438375

Weisinger03
Participant

thanks for the suggestions guys. the cat is going in to the shop tomorrow to see what is going on.

February 14, 2009 at 2:45 am #296404

reelfast
Participant

hey guys im wondering what the water pressure should read on a 2005 merc. 200 efi? i had my P IV out on fork today and the water pressure was reading less than 10 on the guage. motor ran fine, wondering if this could be a bad gauge or a mechanical problem with the engine? also the boat seemed to have quite a bit of water drain out when i pulled the plug out this afternoon. i couldnt find any type of leaks or anything, and the plug was in securely…any thoughts on this as well?

February 14, 2009 at 2:50 am #296405

PhilAddison
Participant

1-3 at idle. 10-15 just on plane. Wide open 15-25. Shoot for minimum of 15 at wide open. If you have a temperature gauge watch that. You should typically run anywhere between 110 and 130 depending on water temperature.

February 14, 2009 at 3:06 am #296406

Bass Cat Boats
Keymaster

Thanks Phil…that was along the lines I was thinkin but wanted to make sure. I know he will be runnin again tomorrow. Ill pass the word.
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