300 I6 rebuild....maybe
 

I have an 81 Ford F-150 with the 300 I6 that sat for several years before I got it. I am not sure of the mileage (I'm at work and the truck is at home). The transmission leaks like a sieve and I think it is just the front seal. The rear main seal on the motor also leaks, but not bad at this point. And my front brake calipers lock up so I think I need to change those and the rubber brake lines. I have never done a motor rebuild, but I am pretty handy with all things mechanical and am not at all intimidated by trying it for the first time. What is my first step in determining if the motor needs a complete tear-down and rebuild, or if it just needs some gaskets and seals replaced. A friend at work told me to check the compression on the cylinders and if they check out, then I do not need a total rebuild. I am trying to just get this truck on the road at this point. I am not trying to make it into a performance engine or anything like that. My daughter needs a car and if I can make this truck my everyday vehicle, I can give her my car. Thanks in advance for any and all input.

Tom

First make sure the things free, turn it by the crank or whatever works. Compression test is a great start once you know its not seized. If the numbers are good then you can just get away with gaskets and external stuff.

My truck leaks from the what i believe is the front seal also, and from the oil pan but i keep an eye on it and never have an issue. (really should fix it someday).

Most stuff on that truck would be pretty easy to replace or freshen up with the motor in unless you feel ambitious and want to pull it to fix the tranny leak. Its all about how much time and money you want to put into it. These motors are pretty built proof and are a great motor to teach yourself with. Hope that helps ya.

-Jesse

o yeah im sure this goes without saying but 100% of fluids should be changed. including brake and dif fluid. Good luck buddy

Does it run?

Sorry about that, but yeah, it does run and I drove it for a little while until I got tired of pouring tranny fluid through it and the front wheels locking up at the most inopportune times.

Welcome to FTE.
Sounds like there a few issues the need fixing.
I agree with StumpPuller,also change all the vacuum lines.Put in a new fuel filter,
have a look at the plugs,maybe a new cap, rotor and wires.Check the timing.
These are all cheap tune-ups.
Then you can get those brakes fixed up.That must be kinda scary.

Ok, did my compression test today. Here are the numbers:

#1 82
#2 79
#3 76
#4 72
#5 88
#6 66

I'm gonna guess that means a rebuild in in my near future.

Also, as I was looking at my tranny, I found the leak was actually soming from the lines carrying the fluid to the radiator, so I think I may be ok with a repair on the fluis line. Anyone got any ideas? I was thinking of cutting out the section with the hole and replacing it with a rubber line using double hose clamps. What do you think?

I agree with rebuilding your calipers. $4 for the kit. Watched a video on youtube and saw how easy it was and laughed all the way to the bank.

Can anyone advise if I need to rebuild based on the numbers above? I saw a couple of other posts where the numbers were in the 110's. I cannot find the actual ford specs anywhere on the net, so I thought I would try here. Thanks to all who responded and I think I am going to do those caliper rebuilds f250 and onus advised.

Tom

[quote=tcmeehan12086;9902618]Ok, did my compression test today. Here are the numbers:

#1 82
#2 79
#3 76
#4 72
#5 88
#6 66

First of all, you need to be using the screw in type gauge. If you're using the 'push it up there' type, then toss the findings. Those findings could mean worn rings, bore, valve seat. The readings should not vary more than 12 to 14 psi. With the #6, I would pour a tablespoon of clean oil into the s.plug hole, and ck it again. If the pressure comes up, then the rings and or bore are damaged or worn. If not, then you may need a valve job or head gasket.

I searched my manual (Chiltons) and could not find the proper readings for your engine.

Thanks F250. I think I will perform it all again. I had problems with the first test gauge and had to take it back to Autozone to get another one. By the time I had gotten back, the motor had cooled down and I forgot to open the throttle all the way. I am gonna try again tomorrow and will post what I find. Thanks again for the help.

Tom

Yeah what restorer said.

And for reference I just did a compression test last week on my close to 70k miles engine. 140-155lbs; I was happy with that. I don't think numbers can get much better than that...

Mine was just like yours when I got it. It's an '81 that sat for a good 4 years where someone just dumped it off. Happened to be dumped off at my father-in-law's ranch, so he finally said if I could get it running, I could drive it away.

All it needed was external stuff. Full tuneup, fresh oil, and about every gasket (minus head gasket) replaced.
All the internals were top notch though. Compression was about 150 across the board.


IF those numbers you listed above are accurate, then the engine's toast. I find them rather hard to believe though. It takes some serious work to get a 300 down that low. I'd definitely get a good tester, warm the engine up, and make sure the tester is nice and tight. Crank it about 5 - 10 times until the needle stops or slows down considerably (easier if you have a friend), and see what comes up.