Ouch. Burned Valve. Please help.

[PH4]

I just replaced my entire exhaust system thinking I had a leak and this was the cause of lack of power and loud popping. Did not work so I sent to a mechanic. He just called me to tell me I have a burnt valve. What are my options? Should I have redone or better to replace with a new engine? If to be redone, any upgrades to do while the head is off? It is a 1972 2.25 with 86,000 miles. In addition, how the h*ll did I burn a valve. Was going down a dirt road fully loaded when it began. Thought the bumpy road had caused the old exhaust to burn/brake through the seal.

How much should it cost to fix this? Any and all advice greatly appreciated.

[badvibes]

feel your pain...

I just replaced my entire exhaust system thinking I had a leak and this was the cause of lack of power and loud popping. Did not work so I sent to a mechanic. He just called me to tell me I have a burnt valve. What are my options? Should I have redone or better to replace with a new engine? If to be redone, any upgrades to do while the head is off? It is a 1972 2.25 with 86,000 miles. In addition, how the h*ll did I burn a valve. Was going down a dirt road fully loaded when it began. Thought the bumpy road had caused the old exhaust to burn/brake through the seal.

How much should it cost to fix this? Any and all advice greatly appreciated.

To start do you have a head that has the "hardened" seats for running lead free gas? If not then that answers one of your questions. If you decide to do the head, I think mine ran about $600 eight years ago, now's the time to upgrade the head for unleaded gas. The exhaust valves deal with more heat than intake valves, heat, normal wear, lack of lead in the fuel to act as a "lubricant" in a head designed for leaded fuel, poor adjustment, anything that allows the valve to not seat well allows just a little leaking to occur around the valve and this probably results in heat building up and degrading the surfaces of the valve and the seat even further. This leads to more leaking and so on and so forth until the valve cannot seat and the cylinder loses compression and we notice loss of power and probably backfiring or popping in the exhaust system. If your motor only has 86K and was running good I'd probably just do the head and run the motor with the bottom end as is. When I bought my truck I knew it had head problems so I started there. After having the head redone I still had a knock in the bottom end of the motor so I had ended up doing the whole motor. Believe me if you can do the head and everything runs good like before you will be $ ahead big time. Another thing you might consider is having the head shaved which will increase the compression which should increase performance a bit.

Jeff

[PH4]

I did alternate putting in lead additive every other fill up. Maybe that was the cuprit. Also noticed prior to event that there seemed to be a powder type oil being blown on the engine from some where maybe the breather caps. It was a reddish clay color.

[PH4]

By the way, the rover did make it the two hours back home with the problem. Albiet with a good deal of loss of power.

[yorker]

I drove one of mine for a good part of a year with completely clapped out valves/seats. Power sucked but it got me home plenty of times.

If the valves were already going then the lead supplement doesn't help much. It took only 10,000 miles to go from OK to toast on that tone.

I bought a new head for $500 and all was pretty good- you may find though that a good head shows the faults in the bottom end...

[badvibes]

I did alternate putting in lead additive every other fill up. Maybe that was the cuprit. Also noticed prior to event that there seemed to be a powder type oil being blown on the engine from some where maybe the breather caps. It was a reddish clay color.

My buddy Scott has a '64 2A also. He doesn't have a lead-free head either. He uses the lead substitute from WallyWorld, it's reddish in color, maybe it's Redline? Anyway he gets large amounts of a reddish sediment in his fuel lines/filters at times. Do you use this brand of lead substitute and have any problems like this? It seems like a lot of sediment to be running thru the filters and has been the cause of clogging the filters at times. I think he uses 3 oz of additive to a tank of gas, not sure about this. Just asking out of curiosity.

Jeff

[Terrys]

An exhaust manifold to head leak is an instant invitation to a burned valve party.

A good automotive machine shop can bore out the heads and install stellite seats. The seats come unground, so the machine shop will grind them and lap the valves in. It's a good idea to punch out the old guides and replace them at this point. Have the head planed to true and then an additional .015" to bring you up to an 8:1, assuming you're starting with a stock 7:1 head. The whole deal will be a fair bit less than buying a bolt-on 8:1 head. It's your choice to replace all 4 exhaust valves or just the one burned one. It's only the exhaust seats that are replaced, so just lap the intakes.

[Jim-ME]

My experience with burned valves has been a result of not keeping the valves adjusted. I have been lead to believe that loose is better than tight.
Jim

[yorker]

A good automotive machine shop can bore out the heads and install stellite seats. The seats come unground, so the machine shop will grind them and lap the valves in. It's a good idea to punch out the old guides and replace them at this point. Have the head planed to true and then an additional .015" to bring you up to an 8:1, assuming you're starting with a stock 7:1 head. The whole deal will be a fair bit less than buying a bolt-on 8:1 head...

I thought it would be cheaper too but by the time I priced the work and the parts that would need replacing ~$500 for a complete new unleaded head was cheaper.

[Terrys]

I thought it would be cheaper too but by the time I priced the work and the parts that would need replacing ~$500 for a complete new unleaded head was cheaper.

Whoa! I just had one done in August, I supplied the seats & guides, but the bill was $325. That was for planing, trepaning the seats and pressing the guides out and new ones in