Hi all, I'm back after a real busy summer.
Anyway, I picked up a '79 Thunderbird pretty cheap. It shows 79,000 and I believe that is correct due to the overall condition of the car. One problem: The 351W in it has about 5 lbs of oil pressure hot and in gear at idle. Cold it shows 45 lbs at idle in park. Hot in park it shows around 10 to 15. This is on a new Sunpro gauge I installed today. The engine has no knocks even at 5 psi. There is some blow-by but no perceptable smoking. I haven't had it long enough to know how much oil it uses. Just a shot in the dark here, but do any of you think I would be lucky enough to just need to replace the oil pump with a high volume one? I would be happy with 15 lbs hot in gear. This is just going to be a spare vehicle, but I don't want to ruin what may otherwise be a good motor.
Comments? Suggestions?
DannyP
89 F-150 4x4 former EFI I-6 now carbed 351W, Edelbrock heads,cam,intake,carb.
MSD 6A, ZF, Sterling 10.25 with 3.55L's.
My 85 F150 has a 351W with low oil pressure when warm. It did it all of a sudden after a 45min highway trip one day, now goes almost all the way down when warm. Never hear any ticking or tapping noises, it started doing this back in spring of 2000, so it's not like that was the end of the motor. Granted, I don't drive her much anymore since I bought a 95 Bronco in fall 2000, but she still runs real smooth and goes all the way to redline without any problems. My mechanic told me it was most likely the bearings (didn't say which ones, I assume main bearings). He had me switch to thicker oil to keep the pressure up, 20w-50, helped some. Personally, I think it will keep going for awhile. I think if you're using it as a second car you should be fine. If you ever start to hear bad noises, call it quits, but until then it'll probably keep going like mine.
Main bearing are allowing oil pressure to drop since there is a larger clearance than original due to engine wear from LACK of frequent oil changes. Yes, you canrun it for a long time like this but don't let it idle long like this as the oil cannot lubricate the top end efficiently if you have low pressure. I would not recommend a hi-volume pump as I have heard that these can destroy your pump shaft to the distributor. If your prepared to drop the pan to replace the pump anyway, drop the crank, have it turned and install a set of matched main bearings. this will probably save you a few more years before a total rebuild
Krosati
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Rosati
64 F100 with a few upgrades.
Thanks for the input but I think I will gradually purchase all the parts to do a complete rebuild then pull it and do it right. I do not relish the thought of trying to install a freshly ground crank while lying under a vehicle and simultaneously trying to prevent 8 rods from nicking the virgin surface.
DannyP
89 F-150 4x4 former EFI I-6 now carbed 351W, Edelbrock heads,cam,intake,carb.
MSD 6A, ZF, Sterling 10.25 with 3.55L's.
Understandable. I had to do this about 12 years ago in a another vehicle that was my only transportation. It wasn't easy and I asked alot of questions before attempting. Fuel line slide over the rod bolts, spark plugs removed, tranny slide back, and alot of cussing, knuckle busting, throwing wrenches and cursing General Motors helped me out alot. I R/R the crank in two days and drove the truck another 4 years before the transmission gave out. Oil pressure was down to 15-20psi at 40mph before and at a strong 60 after.
Your rebuild idea is a much better alternative.
Krosati
Visit my homepage at ClubFTE
[link:www.clubfte.com/users/krosati/|My Homepage]
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Rosati
64 F100 with a few upgrades.
Update.
I dropped in a PAW high volume oil pump tonite. I have about twice as much oil pressure as I had before. I have about 15lbs hot in gear idling and about 45lbs cruising at 55mph. As soon as I pulled the oil pan and seen the original aluminum body oil pump I figured I was on the right track. I am sure the bearings are a little loose but it should last for thousands of miles before I have to do anything major. It has turned into a daily driver rather than a spare vehicle. I like driving it. I just wish they still made 8-track tapes. :-)
DannyP
89 F-150 4x4 former EFI I-6 now carbed 351W, Edelbrock heads,cam,intake,carb.
MSD 6A, ZF, Sterling 10.25 with 3.55L's.
I've seen oil pressure increase bigtime with a rod bearing set change out with a new oil pump....anytime your into pan at least spot check the rod/mains...just my 2cts
