Bad Engine

[latinowarrior]

I just found out that the #7 piston/Head is @ 25 PSI. They tell me that I need to rebuild the entire motor, it will cost about $2,500 dollars. I have a 4.1 engine in the car. Q, can they just fix the bad piston or should I go and have the entire motor redone. The car has over 140,000 miles on the meter. HELP

 

[MAC1]

I remember not too long ago I saw PepBoys advertising rebuilt engines for about $1000. You may want to check the franchise stores i.e., PepBoys, AutoZone, and Advance Auto, about rebuilds. You may get a better deal and a decent warranty; that is, if you’re really interested in keeping the car. Otherwise, how about putting that $2,500 towards a new Cadillac. Then again, you may be able to pick up a used engine at a salvage yard.

 

[latinowarrior]

OK, I'm having low pressure (25 psi) on my #7 cylinder, will I need to replace the motor or just fix the cylinder? HELP Me OUT!!

 

[bufordtpisser]

The simple answer is yes.....................

OK, I'm having low pressure (25 psi) on my #7 cylinder, will I need to replace the motor or just fix the cylinder? HELP Me OUT!!

Yes you may be able to just do a head gasket, valve job, o something else particular to that cylinder. Or if the damage is severe enough, you may need to replace the engine. No way to tell until you tear into it.

 

[MAC1]

OK, I'm having low pressure (25 psi) on my #7 cylinder, will I need to replace the motor or just fix the cylinder? HELP Me OUT!!

What year Eldorado do you own? We are not in a position to give you definite answers, however, 25psi indicates a defective exhaust valve.

Depending on the overall condition of the engine, it sounds like you may only need to remove the head and replace the defective valve, bearing in mind, it's best to have a full rebuild, including valves, valve guides, seals, and seats, especially if you pan on keeping the car. If the valves are in good shape they may need only be slightly ground so they will seal and seat properly in new valve seats. But, of course discuss your options with a knowledgeable mechanic. If it turns out to be a defective exhaust valve, I’m guessing that you can expect to spend in the range of about $400 for a complete head rebuild?

 

[latinowarrior]

My Eldo is a 1984 Convt. Bairttiz

 

[Greg T]

What year Eldorado do you own? We are not in a position to give you definite answers, however, 25psi indicates a defective exhaust valve.

Depending on the overall condition of the engine, it sounds like you may only need to remove the head and replace the defective valve, bearing in mind, it's best to have a full rebuild, including valves, valve guides, seals, and seats, especially if you pan on keeping the car. If the valves are in good shape they may need only be slightly ground so they will seal and seat properly in new valve seats. But, of course discuss your options with a knowledgeable mechanic. If it turns out to be a defective exhaust valve, I’m guessing that you can expect to spend in the range of about $400 for a complete head rebuild?

This is not necessarily true. Could be a burned valve, cracked head, stuck or broken rings, damaged piston or a very scored cylinder wall. Squirt 2 ounces of oil in that cylinder and take another reading. If the compression comes way up you have bad rings. If not it is most likely a burned valve. If the rings and/or block is bad you should just get a reman short block and have the heads rebuilt.

 

[MAC1]

You should be able to check for a valve problem by removing the valve covers and conducting a visual inspection of the valves. If you do not immediately notice any obvious problem, you could then disconnect the battery so the engine does not start and manually turn the crankshaft, perhaps with a torque wrench (if possible), on the crankshaft screw. By turning the crankshaft the valves will cycle, and should a faulty valve condition exist, such as a bent valve or broken spring, you might be able to see it if you know what to look for.

Also, perhaps by removing the main coil/distributor wire(s) (to prevent the engine from starting) you could bump the engine by quickly turning key until the starter engages for a split second then immediately release. When the camshaft lobes move and are not touching valves and so valve stems and springs are fully extended, you should be in a position to conduct a basic examination of the valve springs and stems.

The problem could be a number of things including compression ring problems, valve seat, etc.; however, I was giving him a starting point. As I stated, we cannot give definite answers.