cooling system

[Jerry Stovall]

Have reciently installed a used A4 in my 30' Irwin. Had to combine parts from 3 engines but came up with a good strong replacement that starts, runs good and strong. Cooling problems became apparent first time out after running for about an hour. Up until that time temp remained normal. For no readly apparent reason temp started climbing to 250 and water ceased to flow out of the exhaust and started steaming. After a cool down, begin to trouble shoot from through hull, hose (good flow and can blow back) , water pump (new impeller and seals), thermostat (was open but removed anyway), inlet to manifold, outlet from manifold, hose to exhaust system, muffler (it is less than 2 years old) and exhaust hose. Found nothing amiss. Left hose from manifold outlet to muffler disconnected and started engine. After a moment or two water flow returned. It was hot to begin with but cooled after a few minutes to temp that was not to hot to run on my fingers. Hooked everything up and headed home. It took a while, had to run until temp got to high and then cool but made it.
Decided that first thing to do was an acid wash. Got set up per various published papers and spent most of one day pumping and flushing with good results. Pulled water jacket plate before and after and saw amazing results. Was sure that my problems were solved. No such luck.
I have had the boat out for our local Friday evening races 3 more times and have had the same experience each time. I have examined the whole system completly each time but have found nothing.
Today I dove on the inlet through hull and strainer an checked it out seems to be clear and the flow is very good. I have disasembled all elements once again to study on the problem.
My thoughts on the problem:
Pressure from pump to exhaust outlet seems to be low
Flow at manifold outlet weak
Temp seems to start climbing engine heats, heated engine builds preasure in water jacket slows flow, less flow, engine gets hotter, hotter engine makes steam, steam bubble developes in engine creates back pressure and slows flow even more, engine gets even hotter all incoming water slowed and what little gets into block turns to steam.
The only thing I have found today is upon checking the water pump it is very possible that when I rebuilt it I have installed the seals backward. Could this allow the pump to draw air in to the system and decrease flow and pressure?
Is there any kind of info or picture showing correct seal installation?
Thanks for any comments or ideas.
Jerry

[roadnsky]

Jerry-
A couple of questions...

1) In combining A4 parts, do you have an early or late model engine?
2) Do you know which WATER PUMP you have?
3) Do you know what THERMOSTAT you have? (Holly or Westerbeke? 140 degree? etc.)
4) Have you "tested" the thermostat?

It might help the community "experts" to narrow the issue down.

[Dromo]

pump gasket

By any chance did you make your own back plate gasket when you rebuilt the water pump? These gaskets are paper thin and if yours is too thick it would hinder the performance of the pump impeller
Rick

[Jerry Stovall]

Thanks for your reply
This is a late model engine and am using parts from late models only.

Pump is oberdorfer 202M3. Which I just rebuilt.(new seals and impeller). I am almost sure I have seals in backwards after pulling several spares apart and observing which way lip is facing. Will have to reorder seals as have never been able to get any out without destroying them. I really need to verify what direction is correct.

Thermostat is 140 degree.late model. SS and is similar to one shown in MM parts cat. as part # CSTH 07 60.1 not sure of Mfg.

I have cleaned it in vinigar and hot water and tested it in hot water. It begins to open at 140 and is fully open about 158 to 160 degrees.

This AM I pulled everything down again and scratched, scraped, vacumed flushed and blew into every nook and crevice that I could get to and did get more gunk and debris out of water jacket. I paid particular attn. to manifold after reading a thread that I had not seen before and found more build up that I had not found before. I plan to acidize it more thoughly with preasure flushing and will probably do the whole engine again while I'm at it and re do the distribution cap on the water jacket plate per what I've seen here.

Thanks Again
Jerry

[Jerry Stovall]

Pump Gasket

Used what came with rebuild kit and they are thin also have lapped the surface of plate to remove ware groves when I redo seals.

[rigspelt]

Pump is oberdorfer 202M3. Which I just rebuilt.(new seals and impeller). I am almost sure I have seals in backwards after pulling several spares apart and observing which way lip is facing. Will have to reorder seals as have never been able to get any out without destroying them. I really need to verify what direction is correct.

Using the new forum search tool I found these. Hope they help:

I'm attaching a Q & A that we prepared a short while ago for changing Oberdorfer shaft seals...

http://www.moyermarine.com/forums/showthread.php?t=1664

http://www.moyermarine.com/forums/showthread.php?t=1683

The two seals are exactly the same. When you reinstall new seals, put them in so that the words engraved on each seal face each other. When you reinstall the pump, this will keep the inner (deep) seal sealing out water, and the outer (shallow--actually, flush) seal sealing out oil.

See also http://www.moyermarine.com/forums/sh...ter+pump+seals

[Don Moyer]

Jerry,

Whenever an engine repeatedly works OK for a period of time and then malfunctions, you must look for something that can sequentially do something bad and then correct itself. In most cases, these things require a second or third look, since they might be in their "normal" mode the first time you look. In the case of cooling systems, these kinds of things include:

1) Small pieces of a failed water pump impeller that lodge in fittings (usually the 90 degree hose barb on the discharge of the pump itself). These pieces of impeller have the ability to flop in one orientation such that water will flow quite normally through the fitting, and the next time you use the boat they might randomly position themselves to significantly block flow.

2) The inner layer of rubber in the large exhaust hose coming off of the water lift muffler. In older installations, this layer of rubber is starting to break away from the rest of the hose and crumpling up on itself to cause periodic restrictions (usually after an hour or so of running when the hose gets good and warm). When the hose is cold, the inner liner will tend to shrink up and allow water (and exhaust) to pass quite normally.

3) (Less likely relative to the first two items) Air pockets can build up in strainers and in hoses between the raw water inlet and the pump - causing the pump to cavitate. This issue arises when strainers and hoses are installed so as to be largely above the theoretical water line of the boat, and are most likely in the hottest part of the season when operating in water that has a high concentration of bio-growth. In this situation, gasses normally held in solution are released when the pressure in the strainer and related plumbing is reduced by the pump to create quite large air bubbles. This problem is far less "self-correcting" than the first two.

The attachment addresses your question regarding installation of Oberdorfer shaft seals.

Don

[Jerry Stovall]

Cooling problems

Thanks for info on seals. I also plan to see just how much slop is in the pump housing relative to shaft. When I resealed it I smoothed and polished the shaft with emery cloth. At that time I visually inspected the clearence and it occured to me that it seemed well worn and could be a problem. I plan to disassemble spares and check for wear and pick the best to reseal this time.

The exhaust hose is coming off and will be replaced, it's just as easy to put a new one back on as the old one and there will be no question about it. You won't believe where I have to get my 6' 4" 250# body to acomplish that task.

I am going to concentrate on the manifold acidizing and flushing. I think that it did not get the full treatment when I did it the first time.

I really appreciate the feed back from everyone and have found all posts and historical post very helpfull.

I know there is a solution to this. I've lived with an atomic 4 in this boat for 25years and I know how they are supposed to act.

Thanks Jerry