closed cooling issue merc350i.o alpha1

[freeone]

Re: closed cooling issue merc350i.o alpha1

sounds exactly the same. the reservoir did not overfill that was my mistake, just happened that the fresh water tank for the head was too full and overflowed into the bilge. that was the first time i used the tank, the first time the reservoir emptied and first time i had that much water in the bilge. last week took it out to the lake for a test run after outdrive maint found no water in the bilge but reservoir empty, thats when it hit me, didnt fill the holding tank that trip(no kids).

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

well if i dont get any more ideas by next weekend im just going to replace all the gaskets put her back together, finish comp test and see what happens.

 

[Salt Life]

Re: closed cooling issue merc350i.o alpha1

Good luck to ya!

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

i see one problem though, i just split the riser/manifold was already off the engine. i noticed coolant in the exhaust port when i was removing it from the head but like the head gasket hard to examine since the gasket fell apart during dissasembly.

 

[Salt Life]

Re: closed cooling issue merc350i.o alpha1

Odds are it's your riser to manifold gaskets. To many things would have to be in the correct position ie. pistons and valves, in order for your cylinder to fill up and overflow into the manifold. Plus if that were the case you would by hyraulic locking that cylinder so bad it wouldn't turn over.

 

[Apollo75]

Re: closed cooling issue merc350i.o alpha1

Well, on the overflow it says to fill to this line cold most of the time. Coolant goes out and comes back in depending on the load and internal heat generated --- coolant gets hot and expands ---- has to go somewhere --->> overflow.

If it runs fine like you said earlier --- I would check the cap and make sure it is the correct cap ---- then make sure the proper mix of antifreeze is checked first --- before I got out the impact gun

I should add --- check the overflow tank for cracks.

OFM

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

now that i think about it i did have a hard time turning the engine over after i replaced the gimbal bearing and all bellows last week. . it finally turned over after a few tries, it seemed like something was binding i just thaught it was all the new parts. looking back it was the coolant in the cylinder like you mentioned causing hydro lock.

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

Well, on the overflow it says to fill to this line cold most of the time. Coolant goes out and comes back in depending on the load and internal heat generated --- coolant gets hot and expands ---- has to go somewhere --->> overflow.

If it runs fine like you said earlier --- I would check the cap and make sure it is the correct cap ---- then make sure the proper mix of antifreeze is checked first --- before I got out the impact gun

I should add --- check the overflow tank for cracks.

OFM

i did do a pressure test on the cap and the system before tearing it down, every things within specs. no crack on the tank. as i said i was mistaking about the tank overflowing it was getting burned through the exhaust thats where i was losing coolant to. no cracks on the tank.

 

[JJJ]

Re: closed cooling issue merc350i.o alpha1

If you are taking the heads off, I would have that head magnafluxed and a valve job done.
Just to rule out a warped valve and cracked head.

I have a similar problem on a 4.3 and am going to the stainless blockoff plate instead of the one gasket. Stopleak fixed mine - well stopped the leak.

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

If you are taking the heads off, I would have that head magnafluxed and a valve job done.
Just to rule out a warped valve and cracked head.

I have a similar problem on a 4.3 and am going to the stainless blockoff plate instead of the one gasket. Stopleak fixed mine - well stopped the leak.

i was considering the block off plate. wouldnt you have to use gaskets with that also? my theory was if its going to leak past the gasket itll leak past the gasket for the block off plate(if it uses gaskets).

 

[JJJ]

Re: closed cooling issue merc350i.o alpha1

Yes you use 2 gaskets on each manifold. Can use different gaskets, more crush area, and not a worry about catastrophic gasket failure.

And I'll feel better knowing it is there

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

makes sence, already have 2 gasket sets just need to get the ss block off plate.

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

If you are taking the heads off, I would have that head magnafluxed and a valve job done.
Just to rule out a warped valve and cracked head.

I have a similar problem on a 4.3 and am going to the stainless blockoff plate instead of the one gasket. Stopleak fixed mine - well stopped the leak.

going to start looking for a machine shop. how much should magnaflux run? does the shop have to be marine or just any machine shop?

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

anyone know? or had it done?

 

[Apollo75]

Re: closed cooling issue merc350i.o alpha1

Any good machine shop can do a manaflux and a valve job, check for and surface heads.

I am glad you found your problems

Best of Luck


OFM

 

[JJJ]

Re: closed cooling issue merc350i.o alpha1

No idea on cost to do it, shouldn't be too much though. Alot cheaper than doing a valve job, reassembling it and finding out it is cracked later


Any speed shop should be able to to it, or if you know a good mechanic, they might rec. someone.

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

thank you all for your input, look out for a new post in a week or so of the results.

 

[jtybt]

Re: closed cooling issue merc350i.o alpha1

I just started reading/reviewing your problem. It was suggested quite a while back that the head gasket would cause water to back up into the cooling system and back flow out the reservoir.

There is nothing said that suggests that isn't the case unless your reservoir overflow didn't happen as you first posted.

What happened when you did the leak-down of #6 before removing the head? that should have forced air into the cooling system and would have been very evident.

I also don't understand the head gasket falling apart. It should have been either a solid shim gasket or a SS sandwiched head gasket. The type of head gasket (non OEM) may even be an indicator of a previous head gasket problem caused by overheat and even a warped head that wasn't fixed.

Details and more details help narrow down problems cuz we can't see what you see. Something you don't think significant may very well be key in diagnosis.

 

[QC]

Re: closed cooling issue merc350i.o alpha1

sounds exactly the same. the reservoir did not overfill that was my mistake, just happened that the fresh water tank for the head was too full and overflowed into the bilge. that was the first time i used the tank, the first time the reservoir emptied and first time i had that much water in the bilge. last week took it out to the lake for a test run after outdrive maint found no water in the bilge but reservoir empty, thats when it hit me, didnt fill the holding tank that trip(no kids).

I think he is trying to tell us that the reservoir has never overflowed, only that he is still losing coolant Risers, head gaskets, manifolds, more gaskets, water tanks, head (toilet), magnaflux, pressure testing . . . My guess is a broken flangel rod.

 

[Apollo75]

Re: closed cooling issue merc350i.o alpha1

Well, not to get off subject on the 39-thread on this post

As John Wayne would say --- "There is something a foul here"


Let the big guns throw some thoughts this way.


OFM