older 200 merc rebuild hours?

[giantuna]

rebuilt 200hp mercury has blown head gaskets after 500 hrs. Is this normal?

 

[gss036]

Re: older 200 merc rebuild hours?

I don't know about it being normal, but I tend to change my head gaskets about every 200-250 hours. Salt water can really work on them with the metel ring around the piston hole. Last time mine looked pretty good, time before they were just about rusted out. Maybe depends on who made them, type of metal, etc.

 

[hkeiner]

Re: older 200 merc rebuild hours?

I tend to change my head gaskets about every 200-250 hours. alt water can really work on them with the metal ring around the piston hole.

What frequency would apply to a motor that was run in freshwater only? I am close to 200 hrs on a motor that was run in freshwater only. I have not previously even thought of the need to change the head gaskets. I like to do preventative maintenance with zeal, but also within reason.

 

[gss036]

Re: older 200 merc rebuild hours?

I don't have any experience w/freshwater, I do all my running in saltwater and it really takes a toll on anything metal.

 

[hkeiner]

Re: older 200 merc rebuild hours?

I am probably still good for a long while then, since I am using my motor in freshwater only. One less thing to worry about. Thanks for the reply.

 

[emckelvy]

Re: older 200 merc rebuild hours?

It's not a bad idea to re-torque the head bolts periodically. This may prevent a future head-gasket failure. I'd say once-a-season or every 100 hrs wouldn't be unreasonable.

BTW on the motor with blown gaskets, when replacing you should also have the heads resurfaced to ensure they're flat. If you have recurring head gasket problems, better recheck the flatness of the block's surface too.

Note on salt motors, I like to use a coating of Permatex #3 Aviation-Type gasket dressing on the head bolts. This ensures that salt deposits won't build up around the bolts and sieze them. Probably not a bad idea for motors run on freshwater lakes with hi-alkali or mineral content, either.

At any rate, if you've ever had to remove salted-up head bolts, it's no picnic!!!! You're lucky if you can get them out without breaking any.

If you were to remove each head bolt one-at-a-time, slather some kind of salt barrier on it, reinstall and re-torque to specs, you've likely saved yourself a lot of expensive work in the future.

Just my $.02, HTH.............ed

 

[giantuna]

Re: older 200 merc rebuild hours?

Thanks all for the replies.
I'm new to this site and do appreciate positive responses. From what i've read elsewhere, there are many happy two strke owners with 1,000-3,000 hrs. I've only owned used or re-built so I can't comment on new. I did all recommended maintinance, winterization and operating behavior, but didn't expect the head gaskets to go so soon.

I don't know about it being normal, but I tend to change my head gaskets about every 200-250 hours.

Have you done that since the engine was new? Just wondering if that's the norm.

I fish this boat with a friend and we rely on our mechanics advice. I hope to avoid this situation in the future with the next engine.

It's not a bad idea to re-torque the head bolts periodically. This may prevent a future head-gasket failure. I'd say once-a-season or every 100 hrs wouldn't be unreasonable.

emckelvy-
Do you find that this prolongs the life of your head gaskets?
I can only 'assume' that the heads and block were re-surfaced upon rebuild(not really sure).
I do run only in salt water.
I believe my tech does use salt barrier on the bolts, although both gaskets appear to have been seeping for awhile so the damage is done.

Any other info would be greatly appreciated. Thanks again!

 

[emckelvy]

Re: older 200 merc rebuild hours?

emckelvy-
Do you find that this prolongs the life of your head gaskets?

After head gasket replacement, I'd normally retorque the head once test-ran and cooled off. Then recommend the customer bring the boat back after about 20 hrs operation for a retorque.

The head and gasket will "bed in" after so many thermal cycles of the motor, and it's especially important to get that 20-hr retorque.

With more thermal cycles on the motor, the torque on the head bolts can change and it's just good preventive maint to retorque periodically.

Seen lots of old Johnrudes with 'slack' head bolts and blown gaskets, someone had replaced the gasket but didn't follow-up with a retorque.

It certainly can't hurt that's fer sur!

G'luck with yours........ed

 

[giantuna]

Re: older 200 merc rebuild hours?

Thanks ed, bought it with 80 hrs so I don't know about the 20 hr re-torque.

 

[giantuna]

Re: older 200 merc rebuild hours?

my mechanic says i did good to get that many hrs from rebuild, also said it had been leaking for a while. he rebiult it originally so i trust he knows how long they last. should i just expect to rebuild every 500 hrs? or will something else wear out too?