JB Weld For Cylinder Scoring?

[turtle1173]

Hi all,<br /><br /> Understand that I am speaking from a completely ignorant perspective. Could someone tell me why this wouldn't work? Please be gentle with your rebukes <br /><br />Shane

 

[Kenny Bush]

Re: JB Weld For Cylinder Scoring?

too much heat and stress. If cylinder cannot be bored, it must be resleeved. JB weld.......Man you are going to take some serious heat for this question... And no, Elmers is out of the question.

 

[dilligafda]

Re: JB Weld For Cylinder Scoring?

Not an entirely stupid question, really (from your perspective)The primary reason that JB Weld or other adhesives is that they cause hot spots that lead to detonation and or pre-ignition. Both of these conditions can prove to be fatal to 2-stroke engines. You don't mention what engine you have scored up, but sleeve replacement is an option for some larger engine.

 

[turtle1173]

Re: JB Weld For Cylinder Scoring?

Hi,<br /><br /> The motor is a 1972 85HP Chrysler. I was having problems with low compression in the #2 cylinder. I found out that there was a break in the head gasket. I was inspecting the cylinder walls and there is some light scratches on all 3 cylinders (even the 2 that show good compression). The top of the #2 cylinder wall has a more moderate scratch that I was a bit concerned about. I don't want to tear the engine down. It is likely that when I replace the head gasket, my compression will be back up. Perhaps I shouldn't worry about it until I put the head back on and try it out.<br /><br />Thanks,<br /><br />Shane

 

[jim dozier]

Re: JB Weld For Cylinder Scoring?

JB Weld is an epoxy composite with metal filings as filler. Epoxy is a catalyzed (2 part mix) plastic resin. As plastics go epoxies will hold up to fairly high temps say 300-400 degrees F (somebody here probably knows exactly) but it is a plastic and it will start to loose some of its desirable qualities before it starts to burn. Combustion temps in the cylinder are going to be 1200+ deg F. (the flashing mixture not your cylinder head temp) and before long it would burn off the epoxy leaving the metal particles and some carbonaceous ash. Also epoxy is not very hard and even if you mix it with metal filler it is probably going to be scraped off the walls even if you turn the engine over but don't ignite it.

 

[Squeakit]

Re: JB Weld For Cylinder Scoring?

My limited experience with JB Weld (the fast-setting type) is that it is useless around gas or oil to say nothing of heat. I tried sealing a couple of small leaks in a fuel tank and the repair jobs held for about as long as it took for the fuel mixture to come in contact, let alone being subjected to high temperature, pressure and friction (!) I believe the stuff is overrated - it may be fine in certain cases but it is NOT fuel proof and probably has no tolerance for heat either. JMHO. Replace the gasket and run the engine and don't worry about a few little scratches. Best of luck.

 

[Hooty]

Re: JB Weld For Cylinder Scoring?

JR Weld for a scored cylinder wall? My kinda guy. Actually, I've used JB Welb in a 2 stroke combustion chamber before and it held up pretty well but if you don't want to rebuild and the compression is up and the engine is running o-k, I'd go to 35:1 oil and run it 'til it crokes.<br /><br />c/6<br /><br />Hooty

 

[outboardjake]

Re: JB Weld For Cylinder Scoring?

I don't want to sound like a backyard mechanic, but back in the Chrysler days we sometimes would just change one piston without tearing the powerhead down or even removing it. Remove the cylinder head, remove the intake and unbolt the rod. Quick hone, clean good and put it back together with new piston and rings. Sounds bad but they lasted for years.

 

[outboardjake]

Re: JB Weld For Cylinder Scoring?

By the way that repair was for the people on a tight budget. They were happy as a clam.

 

[OBJ]

Re: JB Weld For Cylinder Scoring?

Hey turtle....<br /><br />Replace the head gasket, run her up and get to operating temp. Let her set that way for a while. May even want to decarb the old girl while yer at it. If you decarb it, let it set as perscribed on the decarb can and run her back up to ops temp. Then shut it down, re-torque the head and do a compression test. If the compressions are with in 5 to 10psi of each other, your good to go. Run it till she drops. I would seriously advise against a rebuild. The old Chryslers just ain't worth it. Try and keep her running as long as you can and then use it for an anchor.

 

[alcan]

Re: JB Weld For Cylinder Scoring?

Hi Turtle<br />I'm going with Outboard Jim on this one. Just slap a new head gasket on her and go. Even if the one hole is lower than spec. As long as the motor runs ok. Let the motor tell you when it's finished. Run it till it drops. Don't hold your breath, it may be a while.

 

[SeaMasterZ@aol.com]

Re: JB Weld For Cylinder Scoring?

off the subject question - Outboard Jim is over 1000 posts, what does it take to make admiral in this rag tag navy????????<br /><br />(no, whoever is in charge of that CAN NOT take the little lady out for a beer!)

 

[Forktail]

Re: JB Weld For Cylinder Scoring?

'72 Chrysler with some light cylinder scratches?...<br /><br />Light hone, new rings. Use the old pistons, but clean the grooves really good before installing the new rings.<br /><br />The head gasket was your problem. No need dumping alot of money into this one.

 

[sharkcat]

Re: JB Weld For Cylinder Scoring?

Can you use silcone sealer for leaky piston rings????LOL

 

[grandx]

Re: JB Weld For Cylinder Scoring?

JB weld... most room temperature cured epoxies are cured with Aliphatic amine, and have a glass transition temperature of 215 F if post cured with excess heat (a little too much info??), JB weld would likelely not last in a combustion chamber long enough for the engine to reach operating temperature. If the scratch is not too deep.. 1-4/1000th's of an inch, hone it ring it and hope for the best. Just my 2 cnts, I'm now going fishin, good weekend to you all, I'll report any catches Monday.

 

[turtle1173]

Re: JB Weld For Cylinder Scoring?

Hi everyone,<br /><br /> Thanks for all the input. I wanted to tell everyone that the people at JB Weld said that their product can withstand 600 degrees when I asked their opinion. If the combustion temperature is as Jimd says (1200+), it is obvious that this wouldn't be the best idea.<br /><br /> Anyway, I didn't use it and just put a new head gasket on. The compression is not the best but even the 2 good cylinders showed lower readings than before. I took the compression at the ramp, right after running it for 15 minutes, so it was still hot. #1-105, #2-90, #3-110 Now if I can get her to shift into gear without dying, I'll be ready to go fishing!!<br /><br />Thanks for all the input.<br /><br />Shane

 

[9675hpforce]

Re: JB Weld For Cylinder Scoring?

no will not wor

 

[blackcreek]

Re: JB Weld For Cylinder Scoring?

Not worth a rebuild, the racing boys mill the heads it is cheap and easy. Take the head to a machine shop and have them take .005 to .010 off the head surface. 20 bucks and I guarantee your compression will go up in all cylinders.

 

[SeaMasterZ@aol.com]

Re: JB Weld For Cylinder Scoring?

thats a great idea blackcreek, seems to be in theory anyway ..<br /><br />if the engine is worn to the point where milling the head is required, isnt the wear on the rings etc going to make the fix short lived? I understand the idea is to squeeze a season or two out of her, but will she be reliable under normal, ie, 80% throttle?<br />Im assuming this is the main kicker, the better gun it, that looks like a thunderhead over thar, wow these waves got HUGE, hello coast guard? HELP! main engine for the boat ... <br /><br />just curious, ive got an auxilliary motor I may be doing the exact same fix to<br /><br />