88 Mercruiser 4.3L with Alpha 1 Overheating

[skibo84]

I'm new to the forum and I got my first question...I just bought a boat and I knew to check the raw water impeller, so I changed it out. It was destroyed. I found alot of the piece in and below the housing itself, but I didn't check the other lines yet. The boat before I changed it would idel for 10 minutes then get really hot (around 220). After I changed the impeller, I made sure to hook up all the hoses and put petcocks back in. I accidently forgot to reinstall the main hoses going into the water pump (front of engine block) and started the engine. After doing this and realizing, I noticed no water coming out. Does that mean that the impeller was installed wrong or what could be my issue here? Also, when I put the muffs on, it seems like almost all the water shoots out around them. It did this before and after I changed the impeller. Also, I took a wire and feed it up through the copper tube that goes from the impeller housing into the upper unit, and I did not feel any obstructions. i also tried this on manifold and risers but not sure what I felt, I just wanted to knock stuff out if it was near the outlet. Thanks for the help in advance.

 

[chiefalen]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

Did you check the long hose that comes from the transom to the t-stat.

How about the t-stat you open it up and see if theres stuff in there?

You got a heat exchanger?

If yes open and clean that out bet you find all kinds of stuff in there.

Than try running it in water.

Still over heating?

Take off the risers.

Tell us what happens good luck.

 

[skibo84]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

I am planning on opening up those hoses tonight...but could I open up the t-stat and just reinstall if it looks okay or should I replace it? Also, I have an open cooling system so I do not think I have a heat exchanger. I never read anything about it in my merc manual.

 

[chiefalen]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

Yea change it out to take it out of the equation.

 

[skibo84]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

I finally got the chance to disconnect all the hoses. I then ran antifreeze through them with all the drains open to see if the fluid would come out. From what I found, there are no obstructions. I plan on changing the thermostat this weekend or early next week. If that does not fix my problem, then does anyone have a clue? Thanks

 

[chiefalen]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

After you change and inspect the t-stat housing ,try running it, if still no water coming out the drive and overheating, than pull the risers.

Might be surprised they are fully blocked or if you have a flapper might have broke loose and blocking the exhaust.

I know some alpha 1's had flappers, more trouble than they are worth.

 

[Bondo]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

I found alot of the piece in and below the housing itself, but I didn't check the other lines yet. The boat before I changed it would idel for 10 minutes then get really hot (around 220).

Ayuh,....

You've got the find ALL the pieces....

The hose at the lower portside of the T-Stat Housing is the line coming In from the Outdrive,...
It needs to be Backflushed of the debris left over from the trashed impeller...

While you have the lower unit off for that, you'd better recheck the new impeller...
You did get the Key inplace,.. Right,..??

 

[Boatist]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

I agree with Bond-O.
You problem is not the thermostat or anything in the engine or manifolds.
If you have no water coming from the out drive to the front of the engine then the problem in in the out drive or impeller. Try back flushing first then recheck your impeller installation.

That hose from the out drive to the front of the engine water pump area should have water coming out like a garder hose.

Once you get that fixed if it still over heats then you can check thermostats and manifoulds

 

[chiefalen]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

I thought you took the long hose off coming into the t-stat and checked to see if it was blocked?

Check it and than like others said back flush with the garden hose turned up high.

You know you have to find the pieces.

All else fails yank the drive off and back flush if good water coming out, than the blockage is in the drive.

Still could be pieces in the t-stat housing also.

 

[MikDee]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

There is only one main water supply hose that comes from the outdrive, and goes into the engine water pump, make sure it's clear, and not kinked between the outdrive, & transom plate. It comes directly from the outdrive water pump (impeller). Water should flow through that like a garden hose, then check the rest of your hoses starting at the thermostat housing, and the thermostat itself to see if they're clear.

There will always be some water escaping from around the muffs with the garden hose on, it shouldn't be a lot, Also, make sure you have the shaft key in the keyway for the impeller, as Bond-o said.

 

[skibo84]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

I check the keyslot when I installed the impeller. I made sure (twice) that it was in the right place.
I took the hose off of the bottom port side of thermostat housing (intake hose from drive unit) and pour antifreeze down it. It all came right out the bottom of the drive from what I could tell (.25 gallons of antifreeze). Should that be an indication that the drive is not block?

 

[Bondo]

Re: 88 Mercruiser 4.3L with Alpha 1 Overheating

I took the hose off of the bottom port side of thermostat housing (intake hose from drive unit) and pour antifreeze down it. It all came right out the bottom of the drive from what I could tell (.25 gallons of antifreeze). Should that be an indication that the drive is not block?

Ayuh,... Not Really...

Dribbling abit of coolant down thru it,..
Compared to Blasting it clean with a garden hose, with the lower unit removed...
Is quite abit Different....

The bit,+ pieces of impeller that are Probably laying in that hose wouldn't even slow down a quart of fluid compared to the required Flow of water, when running...

From your description of your troubles,...
Nothing short of Blasting clean that line is going to help....
I'm pretty certain you have Impeller chunks stuck in there...