302 sounds like a diesel

[paul430c]

Ok, I may have exaggerated a little with my subject line but I DO hear a little knocking from the lower end of my 150k mile 302 at idle. This 77 runs well otherwise but I wonder if I need new connecting rod bearings.

If so, is this something I could do with the oil pan off and the engine still in the car WITHOUT removing the heads? I remember doing an in-car bearing change in highschool but I had the head off so I could remove the pistons from the top.

I appreciate any advice.

 

[taylorB]

It can defiantly be done. very messy and difficult though ;D


Im into air cooled vw's i just had replaced a rod. from the time i pulled the motor, to the time i had it all buttoned up it took 3 hours

good luck with your bearing.

 

[paul430c]

taylorB, thanks for the reply. I guess first things first I need to verify that I actually have a rod bearing going bad. Should I just give it time and see if the noise gets progressively louder?

Photo attached just for fun.

 

[needabronco]

Well if you continue to drive it to see if the noise gets louder, you'll likely be pulling the entire engine due to a rather large and jagged hole in the side of the block from said knocking rod.... But at that point you'll likely know which rod was going out?

 

[Larry B]

I think most cranks will be out of speck when you hear it, and for sure will be if it is a rod bearing and you drive it untill it gets worse. JMO

 

[broncnaz]

Hows your oil pressure? That will tell you a lot. but really if you have 150k on it its probably due for a rebuild anyway I would do a compression test and see what the numbers are. but probably still consider rebuilding it anyway. AS these old carbed engines only last about 150k or so anyhow. either way I'd pull the engine it doesnt take much and will make changing the bearings easier. If you go with new earings I'd put in a new oil pump as well

 

[demesauce]

It can defiantly be done. very messy and difficult though ;D


Im into air cooled vw's i just had replaced a rod. from the time i pulled the motor, to the time i had it all buttoned up it took 3 hours

good luck with your bearing.

But that's not a fair comparison. You can man handle a VW engine out with a floor jack or two. And lift it onto a workspace without an engine hoist. They are super light and simple to work on. I'm a huge fan of old dubs myself

 

[hyghlndr]

Thats a nice looking bronco.

 

[Rustytruck]

High mileage early small blocks are prone to cracking piston skirts. so the noise you have may not be a rod knock. With the mileage you have on your early motor I'd be looking for a used 5.0 to swap in, might get a good one for a couple hundred bucks more than redoing a bottom end on a worn out motor.

 

[paul430c]

Update on my 302

Well, first I want to express my sincere appreciation for the helpful posts. As you can see from my post count, I'm a newbie and just getting to know the forum. What a great collection of people.

With regard to my 302, I don't mind doing a rebuild or a swap sometime but if I determine the noise I'm hearing is not a bearing or skirt after all, I'm going to try to live with it for another year and then make the switch.

I had a wicked oil leak from the front of the engine and I pulled it all down today to replace the front crank seal and timing cover seal, etc. The crank seal was obviously bad. I was SHOCKED at how much timing chain play there was and I'm wondering if that was the chatter I was hearing at idle and not actually a rod bearing. I replaced the gears and chain and I will know tonight when I turn the crank on my work. Photos below:

 

[broncnaz]

Hopefully it was that. Timing chains should be replaced at around the 100K mark especailly on the 1970's engines that had nylon timing gears. The timing was also a little retarded in the 70's so putting a new straight up timing set on can help wake the engine up a little.

 

[paul430c]

Crisis averted

Well, I'm happy to report that a new timing chain and gear set took care of my noise coming from the front of the engine. Everything is buttoned up and runs great. It did 'wake the engine up' a little as Broncnaz suggested. My oil leaks are also resolved and this was the whole reason for tearing it down. Thanks for all the responses. Photos below. As a correction, my Bronco actually has 133k miles, not the 150k I had stated.