Mercruiser 4.3L clear hose test FAIL... SOLVED!!

[trevtt600]

Hello All. I am still dealing with over temp situation on my twin 4.3L mercruisers with alpha 1 gen 1 drives. Just went out this morning and did the clear hose test

I did the flow test before and after the p/s cooler and got the proper flow about 1 gallon in 15 seconds. Actually filled more than one gallon in 15 seconds. After this test, I ran the clear hose from p/s cooler to the thermostat housing. At 1000 rpm, water flow mostly smooth with a bubble here or there. Ran rpm up to 1200 more bubbles, and then up to 1800-2000 mostly bubbles, and big bubbles at that.

I have replaced the impeller and pump housing, but not the bottom plate of the water pump. I don't understand were i could be getting air from the water pump when not on plane. Is it possible that my water pump is not working properly? Can it still pump bubbles or air when you are not on plane?

I'm thinking i need to pull the boat and replace the whole water pump including the base plate with another new unit.

Please let me know what could be my problem.

 

[flyrodman]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Sounds like you getting air in the system somewhere.Is it normal you ask?Not normal.Unless your using soap.Lol.I would run a preasure test.You got a gasget or seal leaking it sounds.

 

[tpenfield]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Where exactly are the air bubbles being seen? The alpha 1 will put pressure in the water intake hose all the way up to the thermostat housing since the impeller is in the outdrive (right?). If you are seeing bubbles at the thermostat housing and they increase with the engine speed, etc. Then I would be thinking about something other than a cooling problem. . . . more like a head gasket.

A blown head gasket will fill your cooling system with a fairly large volume of air and the engine will overheat as a result. So, something to think about if you are seeing the bubbles right at the thermostat housing.

 

[Don S]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Could be the pump base, or the gaskets even. Have you looked at the water pocket cover in the upper part of the drive?
Have you had any serious overheats?

 

[trevtt600]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

The bubbles seem to be traveling up from the outdrive. I have the clear hose on the out side of the p/s cooler. It looks to me as the bubbles are traveling up from the drive somewhere.

The motor runs extremely well, and there is no water mixing with the oil. Oil is clean. If there was a blown head gasket, i would expect some other type of poor running conditions.

Don: I am not familiar with the water pocket cover. Is this in the upper part of the drive? Were the water inlet tube goes? I have not had it on plane long enough for a overheat.

Do you suggest i pull the boat and replace both water pumps with new kits that include the base? Because both motors have the same symptoms, and i put the same type of water pump in each drive.

 

[tpenfield]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

OK, got it.

. . . just wondering if this is when the outdrive is running on the 'ear muffs' or in the water . . . or both. Exhaust bubbles maybe ???

 

[trevtt600]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

The bubbles seem to collect at the inlet to the thermostat housing my buddy said. But you can watch them travel up from the inlet hose. I'm just confused because of the air at low rpms. Just don't know were to start in determining were the air leak is.

 

[trevtt600]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

OK, got it.

. . . just wondering if this is when the outdrive is running on the 'ear muffs' or in the water . . . or both. Exhaust bubbles maybe ???

Running in the water. While underway. We did the test as we were underway down the river, not just sitting still.

 

[Don S]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

The bubbles seem to collect at the inlet to the thermostat housing my buddy said

That's normal, it's where the restriction to the flow is highest. The bubbles get to that point faster than they get through the tstat housing.

 

[Don S]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Do you suggest i pull the boat and replace both water pumps with new kits that include the base? Because both motors have the same symptoms, and i put the same type of water pump in each drive.

I missed the part about twins and both engines having the same problem.
Let's go back to the beginning. This is from your original post about the overheat.

Hello All. We got ourselves a new to us 1986 Wellcraft Monte Carlo with twin 4.3L and alpha 1 gen 1 stearndrives. While it was on the trailer I services both outdrives including all new bellows, gimbal bearings, impellers, shift cables ect... Everything i could replace while it was on the trailer I did.

Did you ever test run the boat before you bought it? or did all the work on it? If so, did it work ok then

 

[trevtt600]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Don: Boat was in none running condition when i bought it. I know, never do that, but i bought it as a project and i enjoy the work. So...

Yes this is from the original post.

I did all the work, but not my first time with this stuff. I have not done the clear hose test on the port motor yet, but it acts the same when on plane. Fast you run the motor, the hotter they get.

Were else could I pickup air from in the inlet hose from the drive? As i stated before, i get proper flow from the impeller just more than 1 gallon in 15 seconds.

Im really leading towards the water pump or something to do with the water pump in the drive.

 

[Don S]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

When you replaced the impellers and upper pump housings, did you make sure the seal was installed in the upper housing? They don't always come installed, and without them when that pump housing comes out of the water, exhaust gasses will get into the water tube. It would also be something you could miss on both pumps.

I see were typing at the same time ............

 

[trevtt600]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Yes we are... Thank you so much for always being here to help out!! You save a lot of people a lot of money!!

And to answer you question.... No, i did not make sure there was a gasket installed there... Did not know about that there seal...

But answer this. Could the exhaust gases be getting into this area at only 1500 rpm or so?

I think you might have solved our problem. Im going to get 2 new kits with bases and all, and install per the book, and not from memory.

 

[Don S]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

But answer this. Could the exhaust gases be getting into this area at only 1500 rpm or so?

Yes.

 

[trevtt600]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Ok. Pulling boat and installing 2 new water pumps. Will return back with my findings. Thanks again Don!

 

[achris]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

This sounds like a classic water pocket cover problem...

http://forums.iboats.com/showthread.php?t=556903&p=3825409&viewfull=1#post3825409

 

[Don S]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

This sounds like a classic water pocket cover problem...

http://forums.iboats.com/showthread.php?t=556903&p=3825409&viewfull=1#post3825409

I've been around boats for a while now, and I have seen 2 overheats caused by melted water pocket covers. Let alone 2 in a row on the same boat at the same time.
Did surprise me that it took so long for you to post that.. Even I mentioned it earlier.

 

[achris]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

I've been around boats for a while now, and I have seen 2 overheats caused by melted water pocket covers. Let alone 2 in a row on the same boat at the same time.
Did surprise me that it took so long for you to post that.. Even I mentioned it earlier.

Yeah, I was asleep until 20 minutes ago... Remember that I'm about 16 hours ahead of you...

When I had my shop I was seeing about half a dozen a year... And we weren't a big shop...

Chris.....

 

[Don S]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Actually it's 14 hours between you and I, but that's not the point. Point being, how often do you loose 2 water pocket covers at the same time on a twin engine boat, after doing major bellows and pump work by the same person that is a DIYer ? (no offence meant trev )

 

[trevtt600]

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Re: Mercruiser 4.3L clear hose test FAIL... But why?

Actually it's 14 hours between you and I, but that's not the point. Point being, how often do you loose 2 water pocket covers at the same time on a twin engine boat, after doing major bellows and pump work by the same person that is a DIYer ? (no offence meant trev )

If im reading this right, you are actually saying that its really not likely to be the water pocket covers, but more the water pump as we indicated before. No offense taken...