Tips to change head GP

[new kid on the block]

Hello to all, I need to change the head GP, on mep-002a. Can anyone please tell me the best method? I am not sure if it would go better with the engine warm or dead cold. I have sprayed some PB blaster on in advance. I sure do not want to break the GP off in the head. I am all ears to tips. One of my mottos is "there is no substitution for experience" .

 

[Jimc]

well after years of working in the marine industry you learn how to remove frozen, salt corroded bolts. the pb blaster certainly wont hurt but i can tell you the best thing is heat. heat is your friend and not the kind of heat from just running the engine. if they are frozen then remove everything out of the way and heat with a torch. slowly work back and forth while hot. have you tried to remove them yet? are they frozen in place? out of the 4 gens i have none were frozen so bad i couldnt get them out. i didnt need heat or any special measures. not saying yours arent frozen. maybe i just lucked out. when you reinstall them, if they are cruddy its nice to run a 7/16-20 tap in the hole to clean it up and then use copper never seize on the gp threads. makes good connection!

 

[new kid on the block]

I have not done anything yet but spray with oil. I sure hope they are not frozen, I do not know for sure. I did read another thread where advice was given to work the plug about a half a turn at a time forward and backward with lots of spray oil. I plan to be as gentle as I can. I would rather take an hour or more to get the plug out safely and in one piece, than hurry and make a bad situation worse. When you say about about using the torch if needed, do you mean to heat the plug, the head area, or both? The unlnown factor for me is just how much torque can the plug take to break it free at the start. I am guessing once it is broken free from the start I should be able to gently work it out in one piece. Another concern I have and maybe it does not apply, I do not know. Is there a chance that the bulb could be swollen? I have read that in trucks it is common. Does ony one have an idea on this? I did not know to use the copper never seize, makes perfect sense. Also sure can not hurt to run a tap through to be sure the threads are clean. Thank you!

 

[Rapracing]

The ones I changed were frozen in and required heat. I heated the plug mainly but I am sure heat got in the head as well. They were swollen in the head. Once unthread I had to apply outward pressure and turn with a wrench to get the end out of the head.

 

[new kid on the block]

I plan to use a torque wrench to take the plug out, so I know how much torque I am using. Any one have any idea what the maximum torque that can be used safely?

 

[patracy]

I plan to use a torque wrench to take the plug out, so I know how much torque I am using. Any one have any idea what the maximum torque that can be used safely?

I'm not sure what you're trying to achieve? Torque wrenches aren't really meant to break fittings loose. Just fasten to a certain spec.

 

[new kid on the block]

You are correct about proper use of the torque wrench. For an example supose you have something that you know needs to be torqued when put together. There is no manual and you do not know the proper torque. If you record the torque needed to break the bolt free, you then have an idea of what to torque the bolt to on assembly. Maybe not perfect yet at least a guide. I sure do not want to snap the GP off in the head. I figure by using the torque wrench when I to try to break the GP loose I can know how much torque I am using. If by chance someone knows the maximum torque that the GP can take before it will snap would be most helpfull.

 

[Jimc]

i doubt you will ever find that information. im sure there isnt a spec for that at all. torque unscrewing something isnt accurate anyway. you just gotta go by feel....more or less. if it starts to turn look at it while its doing it and you'll most likely be able to tell if its actually unscrewing or just twisting.

 

[patracy]

i doubt you will ever find that information. im sure there isnt a spec for that at all. torque unscrewing something isnt accurate anyway. you just gotta go by feel....more or less. if it starts to turn look at it while its doing it and you'll most likely be able to tell if its actually unscrewing or just twisting.

Jimc nailed it.

If I could give you the torque spec of what you could un-torque a fastener at that I've never seen, nor know it's condition, I'd buy a lottery ticket...

 

[Rapracing]

Just like Jimc said in his first response to this thread. HEAT! Use HEAT! That is what they all told me here when I was dealing with mine. HEAT!!

As far as a torque spec that would be impossible. In the perfect world with new or at least clean stuff that is possible. You are dealing with things like rust and corrosion that create more resistance and less material strength. One of the ones I took out had the metal just below the nut nearly rusted completely off. As soon as I put any pressure on it it snapped. I ended up drilling, heating and using an easy out to get that one out. HEAT being the key I do believe

 

[new kid on the block]

OK I got it heat is both my friend and the key. Now; do I want to heat till cherry red? Or heat till the GP is say hot but not cherry red? Those sure are some ugly pictures. The replacement plugs are to be delivered Monday. So it looks like Saturday will be the big day. I agree with Jimc also about to watch the plug for twisting. Well what ever happens, it has to be done. Oh yea!

 

[gimpyrobb]

While I think this is a little more drawn out than necessary, I would try to unscrew it and check for too much resistance. Then I would heat it for a bit and let it cool. The heat cycle will brake the rust bond. Then try unscrewing it again. finally, dump some 50/50 acetone/atf mix on it and torque it on out. At that point if it breaks it breaks.

 

[new kid on the block]

Thanks Robb and all others, nothing like the KISS method, it fits me well. I am glad you did cleare up the part about using heat. I was thinking you all ment to heat the GP and then torque on it right away while hot.

 

[gimpyrobb]

Well, I have had great luck with heating it and letting it cool(like sit for an hour or two after the heat), but if that doesn't work, I might heat it again and twist it hot, or I might just twist it out as in my prior post. For this instance, I wouldn't heat it a second time. Thats just me, others might do it different.

 

[Ray70]

A friend of mine who restores antique outboard motors ( with plenty of rusty and frozen fasteners ) is a firm believer in heating and cooling the nasty looking fasteners a few times before trying to unscrew them. He heats them up with a torch, then sprays them with ice water, then repeats... He also says he sometimes uses hydrogen peroxide ( yes, the stuff in your medicine cabinet ) instead of spray penetrants like PB blaster or WD40 and such. He sprays on the H2O2 and lets sit overnight. Personally, I just uses heat, spray penetrant, then more heat, let it air cool until no longer red and try to remove it and just keep an eye on what is happening. I prefer using a short (6") 3/8 drive ratchet instead of a longer wrench, torque wrench or ratchet, it will give you a better feel and help minimize the chance of applying too much force and snapping it off. If it moves a little then tightens up, apply some penetrant and screw it back in, then work it back and forth while adding penetrant oil.