5,7 Mercruiser overheats

[Ostsideend]

Re: 5,7 Mercruiser overheats

I'm not talking about a compression test. A compression test probably wouldn't show a slight leak from a head gasket or small crack in the head or block, and running compression is lower than cranking compression.
Google "leak down testing" and you will find many articles on how to do it.

Hi Don.
I got it. Thanks. See what i can find out today. 80PSI (5,5 bar) testinf pressure will be enough.
Oliver

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

Hi guys,

i found a problem with the thread's of the screws for the impeller housing. It was impossible to lock these screws. The threads went down like chicken feed without using too much torque. I remember by unlocking this screws to get access to the impeller 3 have been tightend like 85 years grandma does with her left hand. One was almost loose.

I checked the paper sealing. It definitively leaked between the impeller housing and the face plate. Photo comes later.

I changed the poor thread against "step"-studs. I put european standard M8 thread into the lower unit housing and for matching the bores in the impeller housing the studs got a M6 on the other side. You could do this with inch studs as well....

One of the 4 stud's (done on a lath)



drilling base dia for M8 thread



cutting M8 thread with spiral thread drill for "dead" bore



glue them in



and wait for drying

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

... then put some additional liquide sealing onto the sealing papers, but not too much..



and put everysthing together, with the benefit that the impeller housing now can be scewed down with a force that the sealing will work.



It could be THE or one of my problems only.

DON did bring me up to the idea that i have not enough water comming up to the heat exchanger (by restriction or what ever)

I additionally did check with a long thin stainless stell spring (dont know a better word for it) all channels hoses and pipes. There have been no more restictions being found.

I will proceed on pressure checking the heads as well.

Again Don,
many thanks for your help.
Hope i can come back with further questions

Oliver

 

[Don S]

Re: 5,7 Mercruiser overheats

Don't you guys have Helicoils there in Germany?

http://www.helicoil.com/products/helicoil.asp

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

Don't you guys have Helicoils there in Germany?

http://www.helicoil.com/products/helicoil.asp

Yes Don we do and i am used to it but:

• Where to get them on sunday?
• What material they are made from?
• I like V4A stainless steel and a nice nut size
• Like 3 times thread dia for bolt length in cast aluminum
• Much easier to place sealing paper incl. liquid sealing.

Oliver

 

[Don S]

Re: 5,7 Mercruiser overheats

What have you done to that face seal on the top of the pump

That's not how it goes? Do you have the manual? IF not, go up to the Adults Only sticky and download manual #14 then look at section 3B on how to install it.
You don't tuck in the edges inside the pump

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

What have you done to that face seal on the top of the pump

That's not how it goes? Do you have the manual? IF not, go up to the Adults Only sticky and download manual #14 then look at section 3B on how to install it.
You don't tuck in the edges inside the pump

Got #14

What does "don't tuck in the edges inside the pump" mean. Sorry can't catch your words
and: "What have you done to that face seal on the top of the pump" as well.
Oliver

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

Oh now i got you, reading your words again and again.
No it looks like you said but in fact the face seal ist just sitting on top of the impeller housing. I used the "tool" comming with the face seal to place the seal properly. The photo is irritating now me as well. But in fact, the sealing lip is not pushed down into the housing.
I will pull the lower housing again to doublecheck why it looks so compressed.

Oliver

 

[Don S]

Re: 5,7 Mercruiser overheats

Page 3B-77 of manual 14. Shows how to install the face seal.
You have the lower portion of the seal inside the waterpump housing.
The OEM impeller kits come with a tool for installing the face seal. It just lightly touches the pump housing.

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

Page 3B-77 of manual 14. Shows how to install the face seal.
You have the lower portion of the seal inside the waterpump housing.
The OEM impeller kits come with a tool for installing the face seal. It just lightly touches the pump housing.

Used the tool, no edges inside the housing just some mercruiser greese visible.
thanks a lot DON.
You are right it looks like but ist isnt.

Oliver

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

I did a leak down tester to check leak (valves and pistons) as well as for "bubble counting" gasket problems.

Thats the gauge:



Thats the 1mm reducer (0,04 inch) which goes between pressure gauge #1 and #2



I will use it comming weekend.
See what i can find out.

Oliver

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

Got a Mercruiser service bulletin # 95-13It exactly discribes my temp. problem.
They recommend to put an additional liquide sealing underneath the first gasket of the impeller pump which goes against the gear housing. Exactely what i already did.

Hope this could help some of you guys out of fighting with the same problem.
I will not stop searching for other thing to be fixed before season starts.

Regards
Oliver

 

[Don S]

Re: 5,7 Mercruiser overheats

Here's a link to that service bulletin.
http://www.boatfix.com/merc/Bullet/95/95_13.pdf

The fact that the threads in the lower unit used to hold the water pump housing down being stripped out had more to do with your problem than needing a dab of sealer.

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

Thanks Don,
Thats the service Bulletin i was talking about!!

Not beeing sure that the thread problem was the only thing i will do the full programme in checking as much as i can before the boat goes back into the water again.

If it does not hlep - it does not make it worse eather

Best regards
Oliver

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

... it helped...

Fuc.. found water (with antifreeze) in cylinder #7
#7 was a little lower in compression than the others from the beginning on.

Without sparking plugs i turned the engine by the starter motor. Some water sprayed out of #7. The sparking plug told me the rest of the story.

I can't understand that there was no segnificant coolant consumption during riding the boat last year. But over wintertime the coolant had a chance to get into #7 I can't understand the the pressure check of the heat exchanger did not tell me about the problem (0,1 bar within more than 1 min)

I have to get the head off and look for the gasket, the head (pressure check) and the block to procceed.

Anything else i have to check?

Thanks.

Oliver

 

[Don S]

Re: 5,7 Mercruiser overheats

You probably have a problem with an exhaust manifold and riser, not a head gasket. Did you have AF in your manifolds during the winter??????

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

You probably have a problem with an exhaust manifold and riser, not a head gasket. Did you have AF in your manifolds during the winter??????

It's a 1/2 system. I drained the water out of the exhaust manifold before winter. The water which today sprayed out of #7 tasted sweet.

Oliver

 

[sarantis]

Re: 5,7 Mercruiser overheats

Hello from Greece Oliver ,Trying over 2 years to fix my SeaRay which had had a GM305 with overheatig problems and came here from Germany by a Greek guy working in BMW and after finding very slight faults that always made me say 'Now i found it!' i set up a personal test that made me replace the motor because i couldn't trust someody here to rebuild the heads and i couldn't find brand new ones.So, I replaced the incoming water hose with a clear one (there are clear hoses with stainless steel spring embedded in the plastic),and did the same with the two hoses at the exhaust manifold.Starting the engine at low RPM all hoses were ok but when i was reving up the hoses at the manifold were getting full of bubles of exhaust gazes.I took off the heads and i found out why the compression test was giving me only 5 psi lower at the #7 and #8. Although you have different cooling system i think you can do the same test.Good luck!

 

[Ostsideend]

Re: 5,7 Mercruiser overheats

Dear Sarantis,

thanks for the hint with the clear hoses. I have better done this last year when the boat was in the water.

I hope my head or gasket problem will be "visible" after disassembly.

Best regards
Oliver

 

[sarantis]

Re: 5,7 Mercruiser overheats

Dear Oliver,
A lesson i took last 3 years is never to disassemble anything unless you cover any possible test to get more certain.Many things e.g a gas pump may work fine and after disasembly may leak.The test i did ,revealed my problem at dock ,not under load.I sugest you did it using a big barel to sinkthe outdrive (on mufs you ''ll certainly find bubbles ).Good luck!