I keep having trouble with the #8 cylinder burning up. The engine had 150k miles on it when it burnt the exhaust valve in #8 cylinder. I did a valve job and it then melted the piston in that cylinder within a couple weeks. I bought a rebuilt long block and within 900 miles, that cylinder blew the head gasket and melted the spark plug. Apparently the cylinder is running very hot, but I don't know why. This is a different engine than the first, but the same intake(e.f.i.), along with the same oxygen sensor, egr valve, etc. I've been told that the 302 in known for a problem with #8 cylinder, but no one has an answer why.....HELP!!!!

 

Did you check the injectors? It sounds like maybe you have a bad injector on that cylinder. If it's plugged or partially plugged, that cyl will run lean and therefore HOT. At that mileage, it wouldn't hurt to replace them all (might hurt the wallet, but so does replaceing engines). I burned a hole in the #7(I think) piston on a 20k mile Recon engine.

Later,
Jon

 

>I keep having trouble with the
>#8 cylinder burning up. The
>engine had 150k miles on
>it when it burnt the
>exhaust valve in #8 cylinder.
>I did a valve job
>and it then melted the
>piston in that cylinder within
>a couple weeks. I bought
>a rebuilt long block and
>within 900 miles, that cylinder
>blew the head gasket and
>melted the spark plug. Apparently
>the cylinder is running very
>hot, but I don't know
>why. This is a different
>engine than the first, but
>the same intake(e.f.i.), along with
>the same oxygen sensor, egr
>valve, etc. I've been told
>that the 302 in known
>for a problem with #8
>cylinder, but no one has
>an answer why.....HELP!!!!


There is a TSB (#94-4-10) on the 302 engines with #8 plug wire misfiring with the #7 wire. Make sure that the #7 and #8 wires are separated and check that the wires are still in good shape and no burn marks. Try going down to a dealer and have them print out a picture of how the wires should be routed.

Dustin Siebert
mrlaserboy(No Email Addresses In Posts!)
Home Page: http://www.fortunecity.com/silverstone/gear/40
http://www.superford.org/cgi-bin/sf.cgi?uid=default&vr2=1&ID=201
'88 Bronco XLT 302EFI/AOD/BW1356,44IFS(open),8.8(open)/3.55/31"

 

Does anyone know if you can test fuel injectors off the vehicle. The intake is off the engine and the injectors are out of the intake.

 

Send them to RC Engineering (look for them in the back of any tuner magazine) and they will rebuild them for $25 each. They blueprint and flow balance each set you send them. Definitely worth it. If you can't drop $25 each, then look in your local yellow pages for diesel repair shops. They will always have on hand a bench fuel injector tester.

Later.
Randy

 

>I keep having trouble with the
>#8 cylinder burning up. The
>engine had 150k miles on
>it when it burnt the
>exhaust valve in #8 cylinder.
>I did a valve job
>and it then melted the
>piston in that cylinder within
>a couple weeks. I bought
>a rebuilt long block and
>within 900 miles, that cylinder
>blew the head gasket and
>melted the spark plug. Apparently
>the cylinder is running very
>hot, but I don't know
>why. This is a different
>engine than the first, but
>the same intake(e.f.i.), along with
>the same oxygen sensor, egr
>valve, etc. I've been told
>that the 302 in known
>for a problem with #8
>cylinder, but no one has
>an answer why.....HELP!!!!

I would check the fuel rail preassure if its over
45 PSI then it will/can damage #8 cylinder and as earlier mentioned make sure #7 and #8 plug wires are away from each other as they will cross arc.
Good luck

1990 F 150 302 with 31 X 10.50 R 15 and a 308 with C6

 

I had a problem with the #8 cylinder also. It seems that the pvc system for many of the truck and van 302s from about '87 to '94 may have been the cause for this. I have an article that links this problem to the routing of the pvc directly to the #8 plenum, so that the #8 provides all of the suction for this and if the splash guard drain hole inside the valve cover at the pvc suction gets plugged, it can cause oil to be pulled into the #8 cylinder, eventually leading to failure. The routing was changed in '94 or '95 to pull suction from the center of the air plenum (getting suction from all cynlinders) but the key is keeping the splash guard drain hole clean. Mine failed at 68,000 and was under extended warranty, they replaced the #8 piston and put a crank kit in it. Has been better than ever since then. Now has 90,000. I think I still have the article, if your interested.

 

 

I have a 1990 bronco with a 302 and 110K miles. It has the same problem, #8 cylinder has a compression of 30 psi. I would love a copy of that article. I'm thinking the best bet is to put in a new engine instead of a valve job. I would like to get a little more torque and hp any suggestions on what I should have done during rebuild, don't want to go crazy on expense? I live in cal and want it to be smog legal and work with my stock computer an FI.

Any suggestions would be greatly appreciated.

Thanks