Burned Valve Replacement

[Automan1988]

I hava a 92 ranger with a 4.0 and I am certain that it has a burned exhaust valve. At low RPMs it runs real rough and it will suck a dollar bill in to the exhaust. Is it reasonable to find out what head the bad valve is in and only replace the one valve or should I rebuild the entire head? or both? The engine has about 206,000 miles on it so I don't know if it is worth only rebuilding the heads, with out doing bottom end too.

 

[Wicked_Sludge]

depends on what/how the truck is used i guess. if its just a beater, replace the bad valve and lap the shit out of the remaining 11. if its a daily driver, or a vehicle you plan to have around a while, then i'd do the whole top end. new valves, seals, seats ground, heads milled, new lifters, hot tanked...the whole nine. you can leave the bottom end for now and rebuild it later.

 

[fordwheelinman]

were it around 100,000 thousand, id say pull the one head. were it 100,000-180,000 thousand, id say pull both heads. since you are above that, if it were me, id like to at least know what shape the bottom end is in. Id pull it and put it on a stand, pull the heads off, and then flip it over to check the bearings, crank, and the main/rod caps. If the caps and crank look ok, i personally would put in some new bearings, a new oil pump, and pick up tube. And id be doing this while both heads were off being worked. Replace the bad valve, grind the seats, check the guides, and grind the good valves. Thats simply my opinion, and what i would do if the budget allowed.

Having said that, it is pruly up to you. Original bearings can go for 300,000 or more. If the budget doesnt allow both heads, i would just pull the one, even with high mileage, then id save money up knowing i would be going through the whole thing later.

 

[turbo cat]

you can get remanufactured heads assebled for about 300$ a pair at any part store that willn to have the casting problems

 

[Big Jim M]

Was it mine I'd do a compression check and find the exact valve causing the problem...if any.. and then replace ONLY that one valve on my bench lapping it and only it in real good.. Toatal cost would be a gasket set and one valve.. And if you don't have some diamond dust that would be a small expense also..
Big JIm