quick head gasket question

[catfishcarl99]

I just rebuilt a 76 Chrysler 75 hp. got a new head gasket with the sealer in it. so if the heat seals it up should I run it for a min or two on idle to get it sealed up before putting lower unit on or just hit with water on start up?

 

[Sea Rider]

Which method was used to bolt back all cylinder head bolts to powerhead ?

When you have changed a new head gasket with buit in 2 side sealer must torque it with a torque wrench to factory specs. Run the engine for 10 hours as usual and then retorque head back to specs. Gaskets always cede when new and must be retorqued to specs for a perfect seal between both mating surfaces along achieving max compression.


Happy Boating

 

[jerryjerry05]

Run it like you stole it.
You don't really need to retorque.

Add a bit more oil for break-in.
Just don't overdo it.

 

[Sea Rider]

Wer're talking about outboards, right ? With inboards probably a retorque is not mandatory. Both are built with different type of powerhead blocks.

Will need to know if cylinder head was torqued by hand or with a torque wrench, both will give different torque settings as hands don't come with a built in torque wrench. BTW this retorque nonsense, out of the question procedure it's stated on all OB's Owner's Manuals. There are 2 possible choices, the pro way with a torque wrench or the hand way, you decide..

Happy Boating

 

[racerone]

On outboards you retorque head bolts after first cool down.-----Mentioned in many manuals.

 

[Sea Rider]

On outboards you retorque head bolts after first cool down.-----Mentioned in many manuals.

Touche, to each manufacture its own retorque procedure. Short story, if a retorque is not performed on a new head or exhaust gaskets as well or on a new OB for that matter, if boating on salt water, water at pressure passing through powerhead's water paths will make its way around all head bolts threads through gasket.

On next restoration when removing powerhead again will find that many bolts have been fully seized up and will eventually break inside powerhead when trying to be removed which is bad musique.. This post is to acknowledge that this unwanted issue happens very often and it's not mentioned whatsoever in any Service or Owner's Manual. So be fully aware of it.

Happy Boating

 

[racerone]

In a salty water environment some of the bolts might suffer from something called ----" hydrogen embrittlement "-----Look it up if you never heard of it !

 

[Sea Rider]

Thanks, but don't need a tech explanation on that wordingt as have experienced this awful situation myself and seen it too on many other OB's used on salt water. Did you know that the % of salt contents varies from ocean to ocean. Some are more salty than others and consequently bolts will seize up less or extremely more for that matter.

Happy Boating

 

[catfishcarl99]

ok I did all that im just asking if I should let it slightly warm up before running cooling water through it to warm the sealant. I already had it running with the old head gasket to see if it had spark and the timing was on. fired right up and ran it a few times for 2-3 min. when I was done testing it had a bit of milky water in the recirc drain. now its has the fresh gasket on it just wondered about the proper way to seal? wet on start up or dry until it warms up a min or so. I spiked it up with an extra oz of oil in the gallon for the fire up. also a fresh water motor. im in Illinois and this motor hasn't nor will see salt. I have broken this engine down replaced. the carb gaskets, reed gaskets, reed plate gaskets, exhaust chest gaskets, checked the bypass valve and cleaned, replaced the water inlet seal at the engine block plate ,and cleaned the recirc system. all bolts came out with no issue. just wondered if warming up without water seals it better than water immed on startup?

 

[catfishcarl99]

first pic is when I brought it home with 125 152 40 compression reading from a boat mechanic motor horder lol. then what it looks like now. with old head gasket it had 150-148-150 compression after honing and re ringing. the last pic is the 50 its replacing. still runs great but I wanted a lil more hp and I bought two identical model Chryslers for $150 so I have lots of spare parts in case something breaks. two lower units with great gears that have been tore down and inspected and re sealed.

 

[jerryjerry05]

The sealer on the gasket will start to melt as soon as you get the motor warm and
continue to seal over time.

If for some reason the head has to come off??
The sealer will stick to the metal and if not removed the gasket can be reinstalled with
a bit of silicone.
No need to baby it.
If you run it without water??? your gonna ruin the impeller.

 

[catfishcarl99]

well I was gonna run it before I installed the lower unit. but sounds like I just need to not worry about running it with water and just go ahead and assemble it all and just let it do its thing.

 

[jerryjerry05]

That's what they do when you get it new.