Chrysler 757HB. Heating problems (again!)

ErSa

Seaman Apprentice
Joined
Jan 23, 2022
Messages
43
Has resently started up my old 3-pipe. Less than 10 minutes after start the heat light lit up.
Three more start attemts, after cooling, down the headgasket blew.
I am going to put the old piece thogether again with an new head gasket, of course but
the heat problem remains! New inpeller, new gaskets for water pipe, water comes out from the back of rigg .......
1. Could I have put in a wrong headgasket for my motor an that caused the heating problem?
The used gasket has no bana formed holes. See picture #27.
2. What is the funktion of the banan formed holes in the orginal head gasket, se picture #20. The head is, as you se in picture #30 flat?
 

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jerryjerry05

Supreme Mariner
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May 7, 2008
Messages
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The cooling water gets to the head from the two holes in the bottom and top of the gasket.
You have it in backwards? gasket? (had to ask)
The holes in the sides of the gasket really don't allow water to get to the head. Now if the head has corresponding holes then it would get cooling water from them.
Is the head itself clogged? the cover has a water passage for cooling, it could be clogged.
Is it really getting hot? Temp gun (16$ ebay) around the cooling water passages and the head.
Drop the lower unit, hook a hose right to the water tube and see if it gets hot that way?
Did the impeller(old) come out in one piece? all the vanes intact?
Condition of the wear plate and impeller housing?

Water source? hose? bucket? the bucket needs to be DEEEEP. 4-5" over the cavitation plate. The pump is NOT a self priming pump and needs to be under water to initially pickup water.
Muffs? depending on the drive/pickup the muffs might be wrong? pics of the lower unit showing the slits for the water pickup.
 

ErSa

Seaman Apprentice
Joined
Jan 23, 2022
Messages
43
1. Gasket turned backwards?????
2. Head not clogged.
3. Motor got hot running on boat. 105 centigrade at thermostat and 80 C at middle cylinder (IR thermometer).
4. Waterpump is the old type with no seal round drive shaft, 6 wings. Se pic.
Question: Is the waterpump with seal round drive shaft a better one than the one without seal round drive shaft? Better with 12 wings impeller?
 

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jerryjerry05

Supreme Mariner
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May 7, 2008
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Answer the rest of my questions.

Pics of the drive?
6 or 12 really makes no difference.
I think the 12 vane impeller is the older style.
They push enough water to make up for the seal or no seal.
Turned backwards: the hole at the bottom when backwards it blocks the water from going to the head.
Thermostat installed?
What are you using? bucket, hose with muffs?
Some muffs won't work on certain drives.
 

ErSa

Seaman Apprentice
Joined
Jan 23, 2022
Messages
43
1. Then the motor got hot it was driven on lake, 3000 rpm..
2. Themostat open at 60Centigrade and close at 55 Centigrade.
3. Water pums looks OK?

Suming up: Check if cylinder head is warped. Buy new head gasket.
Install head gasket turned in the RIGHT DIRECTION! Reinstall used water pump.

Thanks for all ecessary advices.
 

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ErSa

Seaman Apprentice
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Jan 23, 2022
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43
Never ending story ......
Nordin told me that you can´t turn the head gasket the wrong way.
Perhaps the gasket has cracked in the fist way and the exhaust gases leaked out into the cooling water canal and caused hight motor temperature?
Joke: Chrysler always give you challenges.
 

Nordin

Commander
Joined
Jun 12, 2010
Messages
2,428
ErSa, check the head for warp with a straight ruler.
Not more then 0,10 mm feeler gauge able to go through. Most important around the cylinders.
If more, grind it at a piece of glass with a water grinding paper in a eight (8) pattern.
Install a new head gasket and torque it in 3 steps and start in the middle and do it in a circular pattern, ccw.
Warm the engine up at idle and let it idle for about 7-10 minutes.
Then retorque the head bolts and do it in 3 steps again and start in the middle an go in a circular pattern.
Just for checking that the impeller is working right, run the engine without the thermostat for a little time.
The thermostats purpose is to open up the cooling water to circulate through the water jacket around the plugs in the head cover.

After some hours of running it do a retorque of the bolts again.

I think you blew the head gasket and got compression in the water jacket and it start to get less cooling water cause of compression.
 

Nordin

Commander
Joined
Jun 12, 2010
Messages
2,428
Looking at your pics closer, how is the surface between cyl. 2 and 3 exactly where the head gasket failed.
Looks like the surface is not flate.
Can be a wrong interpretation of the image.
 

ErSa

Seaman Apprentice
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Jan 23, 2022
Messages
43
No compression in cylinder #3 after overheating.
I have decided to run British instead.
Over and out, until further notice.
 

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jerryjerry05

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You'll be cruisin with that Seagull.
Get another 10-12 and you might be able to tow a tube. :)
 

ErSa

Seaman Apprentice
Joined
Jan 23, 2022
Messages
43
Feed back.
I think I have a Chrysler 75 hp that is not owerheating now. Ran it for 5 hours.
I have:
1. Located the TDC using an indicator clock. There var something wired with the timing pointer. From an other motor?
2. Changed the water pump from a type without top seal to a type with topseal.
Perhaps this was the problem/s with the overheating.
 

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ErSa

Seaman Apprentice
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Jan 23, 2022
Messages
43
Feed back. Forgot one more important measure.
3. Cylinder head been planed.
 
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