4.3 vortec 2008 aprox. Alpha one 1985 s/n A802400 Overheating

[Eric Bornstein]

I have read many of the posts on overheating. Last winter the Intake manifold froze as I did not drain it ever, now I know it does not drain completely with the engine drains. I have changed the exhaust manifolds and intake manifold this year. I changed the raw water pump a few years ago when it was overheating over 3000 rpm and cleaned out the risers and that seemed to work. This year I also had intermittent starting problems,cleaned all contacts and changed the distributor cap, coil and pickup module. Likely the module and it starts and runs well, also timing reset. I put a clear hose on the raw water feed to the power steering cooler and ran it into a bucket. Flow seems good and no bubbles. With the muffs on and 50 degree water feed, the exhaust manifolds and risers stay cold as does the big hose that leads to the circulation pump. I changed the thermostat (140 degree) It now holds temp until revved to 2000 and then slowly climbs to just bellow the red mark on the gauge and reads up to 225 with a temp gun at the base of the thermostat housing. Should I be looking at the circulation pump? Also is the slot next to the thermostat supposed to be covered by the gasket?

 

[Bt Doctur]

Also is the slot next to the thermostat supposed to be covered by the gasket?

Nope, need to be open to allow bypass water to the elbow

It now holds temp until revved to 2000 and then slowly climbs to just bellow the red mark on the gauge and reads up to 225

Can`t rev it that high on a tank or using muffs

 

[alldodge]

I changed the thermostat (140 degree) It now holds temp until revved to 2000 and then slowly climbs to just bellow the red mark on the gauge and reads up to 225 with a temp gun at the base of the thermostat housing. Should I be looking at the circulation pump?

No not yet, you should not be reving more then 1200 and that's pushing it. Your garden hose does not supply enough water

Also is the slot next to the thermostat supposed to be covered by the gasket?

No, it is the bypass area until the thermostat opens

 

[Eric Bornstein]

So I am surprised that I didn't get a gasket in the kit with the cutout but also did not see why the slot would be covered. I will try it with the slot open. I did not notice the water level drop in the large bucket I have the foot in with the muffs on, however I may not have looked at the right moment.I will order a new raw water pump in case that turns out to be the problem and to change it for next year. I was overheating on the lake after I had changed the module but had not reset the timing and when I got home I found it off (retarded) by a few degrees. I guess I will try it in the lake again.

 

[alldodge]

That doesn't look like tha same kit 807252T3

https://www.mercruiserparts.com/807252t3-thermostat-kit

 

[Bt Doctur]

 

[Eric Bornstein]

Looks like I got a t4 kit in the wrong pkg ....

 

[achris]

.... I put a clear hose on the raw water feed to the power steering cooler and ran it into a bucket. Flow seems good and no bubbles. ...

For this test to be valid, you need to put the clear hose in the line and take the boat out and run it under load, while watching that clear hose for bubbles. You could have the worst leaking water pocket cover on the planet, but on flushers, it still wouldn't show up.

Chris.......

 

[Eric Bornstein]

Thanks to all for the advice, Clear hose is setup and thermostat bypass slot is open. I have to wait till Thursday for nice weather to try again. Will let you know the results.

 

[Eric Bornstein]

Tried it, still heating to bottom of red but I did not set the timing correctly as I have only 1 mark on the damper that I was setting it to (TDC), I believe I am off 6 degrees. While I was out I had a gimbal bearing failure and required a tow back to the marina. I have removed the outdrive and found water in the bellows and the failed bearing. The U-joints may have problems also. TIme to renew bellows, bearing, U-joints, water hose, and maybe senders. Anything else while it is open? Is the Gimbal pin removing tool a standard 12 point tool? My pins look like a hex 1/2", is it 12 points deeper in?

 

[achris]

We sell hinge pin removal tools here at iboats.

 

[alldodge]

4.3 vortec 2008 aprox. Alpha one 1985 s/n A802400

Could you you clarify what you have so I can understand the possible variables?
What year Alpha drive?
The thermostat housing is a 1985 type, but what year are the exhaust manifolds?

Do the hoses route like this

 

[Eric Bornstein]

The exhaust manifolds are aluminium,new this year. The cooling system is as in the diagram above.Manifolds and Risers are cool ( under 130 ). The 6 degree retarded timing could cause the overheat,no bubbles in the raw water supply. I see from the reviews for an older drive like mine I should purchase the quality hinge pin removal tool.

 

[alldodge]

The manifolds are older style wet ones?

and your using Vee belts not serpentine?

 

[Eric Bornstein]

Manifolds I believe are the wet ones, same as my old cast iron ones. Belts are Vee.

 

[alldodge]

Sorry if I missed it, but scanned back thru the post and did not see.
When the gauge starts climbing, have you used a IR temp gun to verify that the temp is actually going that high?

 

[Bondo]

The exhaust manifolds are aluminium,new this year. The cooling system is as in the diagram above.Manifolds and Risers are cool ( under 130 ). The 6 degree retarded timing could cause the overheat,no bubbles in the raw water supply. I see from the reviews for an older drive like mine I should purchase the quality hinge pin removal tool.

Ayuh,...... Welcome Aboard,...... What is the t-stat housin' ya usin',..?? '08, or the '85,..??

I once ran into such a situation, of a later 4.3L('94/ 95 Alpha, Gen.II), that was mated to an older Alpha 1(approx. '85),.....
The t-stat housin' on the later motor didn't have the check-balls in it,......

'n without the check-balls restrictin' the discharge water, it ran hot at idle,.....

Put check-balls in the t-stat housin', 'n a Globe run-dry impeller in the drive, 'n never overheated again,......

Marine exhaust manifolds are Always, Wet,......

The difference is whether plumbed Warm, or Cold,.....

 

[alldodge]

Marine exhaust manifolds are Always, Wet,......

Sorry, I meant are they dry joint or wet joint?

 

[Eric Bornstein]

I believe the manifolds are fed with warm water and the risers with cold. I am not sure what dry joint or wet is, the joint is gasketed with some silicone seal. The check balls are there. Temp was checked with a gun at the base of the thermostat housing 185 to 225 with the needle just below the red zone.

 

[achris]

A 2008 engine should have dry-joint manifolds. But if you bought a long block and fitted it out it may have the older style (often referred to as 'wet joint') manifolds.

Here's the easiest way to tell them apart without taking the elbows off the manifolds.


Here's what the gasket surfaces look like, and then you'll understand how they get the names (note the water passages so close to the exhaust passage on the 'wet' joint). On the dry-joint, the water flows though the large holes for and aft of the exhaust passage.



Chris.........