I am new to the site, but I need some help. I recently picked up a 1990 4x4 F150 with a FI 300 in it. I believe that it needs a rod bearing or bearings replaced.

I know it won't be fun, but can I replace the bearings both main and rod without pulling the engine?

I currently just need to drive the truck and would rather not go through the R&R process at this time.

I have heard of people jacking the engine up and removing the pan and doing it that way. Has anyone here tried that one?

Any advice for me?

I appreciate your time, ROB

 

If it needs new bearings,be prepaired to pull the crank too. I have a camry that needs new bearings and it chewed up the crank. Not only did it chew the crank but the rods too.....I hope you don't need to replace bearings......

What makes you think it needs new bearings?

 

I agree with mr. cruise.

If your bearings are shot, your crank might need some workin too. Mine does. As for jacking up the engine and taking off the oil pan, that just seems like a pain to me. I'd rather pull it completely out, it was easy, took no time to completely strip the motor apart. Then you can see everything and know what needs replaced. It took me and my dad 12 hours to pull the motor/tranny, and strip the motor apart. Once the motor is out and on an engine stand its cake. Getting the 300 out of there is a tight squeeze though.

 

The deal is that the truck is a bit rough. It has sat for about 7-8 years and has alot of miles on it.

It will start and run and then about 15-20 minutes later there starts a slight knocking sound. It isn't a real scary sound....... yet. As quick as I heard that I shut it down. It wasn't a tappet type of sound. There was enough oil in it although I am not sure on the viscosity of it.

I am aware that the best thing is to pull it out, and I may do that.

I just want to know if anyone has done it. I have heard that the 302 was pretty tight. I would imagine that the 300 is even tighter.

Thanks for the input, ROB

 

...Welcome toyotajeep, to Ford Truck Enthusiasts!

We are happy you have chosen the best source for Fords!

Enjoy FTE....and
JOIN CLUB FTE -SUPPORT THE FORUMS!
…..See you on the boards.

 

Happy to be here. It seems that you have a nice board culture here.


Have a good day, ROB

 

Changing main bearings can be done without pulling the crankshaft out, but you would have to drop the transmission down and if your already that far in to it another hour worth of work and you can get the engine out so it may not even be worth it to leave it in the truck. Its done in the truck industry all the time, its known as a bearing "roll in". You just lower the crank about 1/4" and push old bearings through and roll new ones in.
To change the rod bearings all you have to do is remove the pan and take each rod cap off. Do them one at a time so you don't get any of the parts mixed up as they will need to go back in the exact same place they came out of. Also be sure not to turn the piston in its bore when the rod cap is off as that might move the rings and break their seal.......on an older engine very important. Best way to keep that from happening is not to move the piston when its unbolted. Take the rod cap off and then turn the crankshaft to get the bearing out. Then put the new bearing in and turn the crank back up in to the rod. Also note the bearings have an upper and lower that need to go in the correct position, identifyable by stampings on the outside of the bearing.

 

OK. I think I will go ahead and lift it up and see if I can get the pan off and take things from there. I'm deciding on what is the best direction from here. For me personally, if I have to drop $1500.00 for a rebuild with incidentals it is probably not worth it to me. I just need the truck for dump runs etc.

I wasn't sure on the roll in operation if I needed to drop the crank or not. Sounds like I do.

Thanks for your help, ROB

 

This engine has a one piece rear main seal and you can't take the rear main loose. Does it carry any oil pressure? If it has set a while you might flush the pan/ oil system drain the oil out put in 5 or six quarts of diesel and run if for 5 mins then drop everything put on a new filter and oil and see wht happens. Some times when they sit like that the oil pickup screen gets gummed up.

 

If you do need to have the crank worked,I would get a "Crank kit" instead of havign the old one machined. That way,you keep standard size bearings and it isnt that off. Make sure when you put the new bearings in,you lubercate it really good! Leave the outter side of the bearing and inside of the rod cap dry,but where the bearing attaches to the crank,put plenty of grease there. Better yet,if you want to do this yourself,get a Haynes manual and it will tell you how to do it. Spun bearings suck.....


EDIT:Wait,if it sat for years,You should of changed the oil before you cranked it up anyway.

 

before doing anything try a different weight of oil.

 

I agree on the changing the oil first thing. I should have done that, but I do want people to know that it was parked because of the mild noise. This was a problem while it was a dailly driver for the PO.

I actually got the front end up, the two nuts off on the mounts. Tomorrow I am going to pull a quick compression check on it. If it looks good, I will lift it up and drop the pan. And see what I have.

I didn't say anything, but I am a shop teacher, including automotive. I was more curious about the process that people have used/difficulty rating of the pan removal process.

I appreciate the other news though. I have thought of some thicker oil etc. but I think it is just a loose bandaid at this point.

I should have some more information later this week.

Thank you for your input, I do read and appreciate it.

ROB

 

I got all the main and rod bearings in a 390 once from underneath. I didnt have to lower the crank at all. At least no lower than it goes naturally when the caps are removed. I cant say what the result was because after all the effort I cound'nt get the nightmare two piece rear main seal replaced properly from underneath. Needless to say I had to pull that engine and went ahead and did a complete overhaul.

To me the truth of the matter really is the fact that any engine that has seen enough use to wear out the bearings will need rings, camshaft, lifters, timing components, and all gaskets and seals as well. I would never try to repair a worn out engine like that again. Its ok I guess if you are the type to not mind always patching things up and turning wrenches all the time. I found so mutch satisfaction in knowing that my 390 was right. No questions, or wondering what is going to happen next. This experience really changed my outlook from patch it to fix it. No other way........

 

On the other hand, if, as he says, the truck is just for dump runs etc., the economics of the job are his first consideration. It's not a bad idea to just jack the motor, pull the pan and take a look at the rod bearings and inspect the journals. Then make the appropriate decisions.

 

Drain the oil like a day before you pull the pan/do work under there.....so the oil doesn't keep dripping onto your face....