closed cooling issue merc350i.o alpha1

[Glastron_V210]

Re: closed cooling issue merc350i.o alpha1

If it's losing coolant, but not into the bilge, then the manifold/riser gaskets are the likely culprit. Use the acetone test to confirm. Or, renew the gaskets and reassemble and test. It could also be a heat exchanger internal leak, which will push coolant into the raw water flow. They are the big two leak points. To check the exchanger, pop off the end plates, block off the fresh water coolant passages and fill the passage with 10psi of air. Place the assembly in the bath tub full of water and look for bubbles. No bubbles, no leak.

After they are tight, then:

1) Assemble, but don't fill with coolant

2) Using the cap tester, fill the entire system to 10psi of air, then valve off

3) If the air pressure is maintained, you're good to go. If not, get snoop (leak detection fluid) or soapy water and check your hose connections. Check your thermostat gasket. Everything. Find, fix and repeat. If you can't find the leak externally, then it's either heat exchanger internal leak, head gasket or cracked head.

Now, you have a fair bit of confidence in your closed cooling system.

Fill er up and go for it.


Chay

 

[freeone]

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.

1. overflow of reservoir never happened
2. on#6 cyl i stoped when coolant came out about a cup
3. the gasket left pieces on the block and pieces on the head, difficult to analyse. ss sandwich type.
4. taking heads to machine shop for testing. will start a new thread after results.

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

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.

you are correct sir, water tanks for the hed(toilet) were the culprit for water in the bilge, it was just a coinsidence. going to get the cylinder heads tested install ss block off plates and gaskets on the risers, head set will be here on monday. will put back together do a complete leakdown, comp test and cooling sytem pressure test and post results next week on a ney thread. what is a flagel rod?

 

[QC]

Re: closed cooling issue merc350i.o alpha1

A flangel rod is my favorite engine part. Mythical and non-existent, but it sounds real and expensive . . . Sorry :redface:

 

[JJJ]

Re: closed cooling issue merc350i.o alpha1

I prefer either

A. Chrome plated piston return spring
or
B. Shoe shoe valve

 

[freeone]

Re: closed cooling issue merc350i.o alpha1

gotcha. heads are at the machine shop getting full workup. was cheaper than i thought.