Engine knocking – 1972 FJ-40 F Engine

[rover67]

I'd poke around with the stethescope and see what it is. belt back on, poke alternator. should be deafening if it's bad..... Like no question as to what it is with the stethescope. You just touch the parts and can hear them, if you touch the front of the water pump housing for example you will probably be able to hear the bearings, same with alternator, should be able to just hear bearings if normal. loud bearings if bad etc.

 

[rover67]

I guess in short I wouldn't go throwing parts at it before determining what the source of the knock really is.

 

[simps80]

a1 auto electric was the name like 30 years ago
then like a1 base or a1 best
then they got bought by mobile diesel but still have a1 in the name

there’s others too but that’s the OG i use/used
they’re on newport in commerce city not the old a1 auto electric location

 

[72 FJ40]

A-1 Best Alternator Starter Exchange
Address: 5567 Newport St, Commerce City, CO 80022
Phone: (303) 287-3347

 

[wesintl]

you can get a cheap alt from rock auto up to the more expensive. City racer has a sourced replacement i can't tell if its a remy or what. probably nice to have a spare and rebuilt the oem. Change out the water pump and call it good

 

[RDub]

Water pumps can make an awful knocking sound when they are cavitating, which can happen with very low coolant level or if overheating. Your issue doesn’t seem like it’s cavitating based on your description of events, but it is yet another knock source.

 

[72 FJ40]

I was being cautiously optimistic but I'm afraid I think I have bad news. I went to Harbor freight and bought a stethoscope and listened to the alternator and it just sounded like a brushing noise, to the water pump and just sounded like bearings rolling. I really couldn't give it that much gas when I was checking underneath on the oil pan but I did hear some knocking in that area. I obviously have not been running it very long when I do these things. It was low on oil when I got home. I had just changed the oil… And adjusted the valves and set the timing about a month ago. When I returned home it was about a quart and 1/2 low. I've never had a drop like that maybe it's because the valves weren't adjusted right… I did not just readjust the valves or even check them but I will do that. I did check the compression of the engine though, the readings are little low probably because it really wasn't brought up to full running temperature. Nothing seems catastrophic there.

Cylinder	Before Knocking	After KNOCKING
	Dry​
1	133​	130
2	125​	125
3	138​	130
4	128​	128
5	130​	122
6	132​	140

Of course I put more oil in it… And that might be why the knocking has gone down. Especially that I ran it. I did take the valve cover off though and all the valves/rockers appear to be getting oil and functioning properly although I did not check the settings.

Forgive my ignorance here…

I know that it is possible to change the rod bearings with the engine still in the truck. Is this a bad thing to do?
Should I check the valves?
Should I drain the oil and drop the pan and so I can get a closer look?
Should I order some rod valves… In case it's just one of them that's knocking and just fix that so I have them on hand? If that is the case they come in different sizes and which size should I order just the standard one?
Or do I need to pull the engine and have everything inspected?
I heard too that the oil pumps for the 1F are not available but the 2F are but you need to use a 2F oil pan? Does anyone have experience with doing this? Is that something I should do. I'm sure it is if I'm going to rebuild the engine.

Again I did not really run the truck very long and it didn't really even get up to full operating temperature.

Any thoughts or answers to my questions would be greatly appreciated of what I should do next…

 

[Cruisertrash]

D and D Auto Electric on 44th west of Kipling in Wheat Ridge

 

[72 FJ40]

It wasn’t the alt or water pump… with stethoscope on oil pan I heard knocking… I still have good compression… should I readjust valves before dropping the pan? Just drop the pan and inspect? The pressure was just ok (see above). I guess you can’t inspect rings without pulling the engine. Is it best to pull the engine?

I just have time tomorrow and wasn’t sure what next step was? Please read my previous post to see where I am on this. My guess is to drop the pan and inspect. Let my know your thoughts.

 

[Crash]

My two cents is worth what you paid for it but pulling the pan would be my next move.

 

[Rzeppa]

If you do drop the pan, be aware that there will be dripping for hours and even days. Wear safety goggles, a hat and cover yourself with something you don't mind getting oil on, like a sheet of plastic.

Consider pulling the plugs so you can rotate the crank more easily to get at each rod end.

 

[72 FJ40]

I am starting to think about it and I have the time and money right now and the weather is good. I think I should just pull the whole engine and that way it will be easier to inspect and see what I need to do on a full rebuild. I already had the head rebuilt three years ago.

Can somebody be explained to me why I wouldn’t pull the engine and the advantages of checking out the crankshaft with it still in the truck. I guess I have decent compression. I’m looking for somebody to play devils advocate, cause I don’t really see the advantages. Unless somebody thinks that my compression numbers are high enough to not justify a rebuild. I’m just trying to be open minded since I’ve never pulled an engine before and I am kind of a newbie to this part.

 

[Rzeppa]

First of all, compression numbers have nothing to do with rod knock, completely unrelated to each other, so forget about compression and concentrate on your original post. Valves have nothing to do with rod knock. You either have rod knock or you don't. You said when you removed the belt the knock went away. Then you said that with the stereoscope the was no sound from your alternator or your water pump (assuming those observations were after you put the belt back on). So those observations are kind of contradicting each other.

One of the thing about rod knock, when it is caused by a worn rod bearing is that it will become much more pronounced when the motor is under load than when is is just sitting there idling. Think about it. A worn out rod bearing will allow the con rod to bump up and down on the crank and make a big noise when the crank is under load rather than when it is somewhat relaxed just idling.

Drive around the block. punch the gas. Listen to the magnitude of the knocking. If the knocking gets way worse under heavy acceleration, yeah it could be a rod bearing. The chances are pretty slim that you're gonna have what I had driving 75 MPH on I-70 coming back from Cruise Moab versus driving around the block, as far as throwing a rod into the side of the block. Again, a different time I had knocking that was my alternator, and taking the belt off confirmed that. My alternator was original, like yours.

 

[Rzeppa]

Oh and what I said up thread, the guy who made that video was, shall we say, inexperienced. It appeared to me that was his first rodeo and he just wanted to become famous with a Youtube video. Andy was correct to point out that the guy eventually got his motor out. He just did a bunch of stuff that was unnecessary and pretended to be an authority. And of course as was pointed out above, he never mentioned, oh yeah, undo your battery cables, starting with negative.

I've been driving and working on old 40s for over 40 years, and pulled, replaced, rebuilt and reinstalled many F and 2F engines in 40s over those decades. Both mine and other Rising Sun members. There's a bunch of stuff you learn from doing it many times that the guy in the video hadn't learned yet.

If yours were my rig, I'd replace the alternator first. If the knock was still there, then boom, you have a different issue. If the knock goes away, wipe your forehead, change the oil every 3000 miles and drive that thing with a smile on your face.

I change my oil and filter every 2,500 miles 'cause it's easier for me to keep track of than the 3000 miles it says in the owner's manual. 255000 miles, 257500 miles, etc. My 1976 FJ40 has over 273,000 miles. And yes, I've pulled that motor a couple times and rebuilt it once.

 

[72 FJ40]

First of all, compression numbers have nothing to do with rod knock, completely unrelated to each other, so forget about compression and concentrate on your original post. Valves have nothing to do with rod knock. You either have rod knock or you don't. You said when you removed the belt the knock went away. Then you said that with the stereoscope the was no sound from your alternator or your water pump (assuming those observations were after you put the belt back on). So those observations are kind of contradicting each other.

One of the thing about rod knock, when it is caused by a worn rod bearing is that it will become much more pronounced when the motor is under load than when is is just sitting there idling. Think about it. A worn out rod bearing will allow the con rod to bump up and down on the crank and make a big noise when the crank is under load rather than when it is somewhat relaxed just idling.

Drive around the block. punch the gas. Listen to the magnitude of the knocking. If the knocking gets way worse under heavy acceleration, yeah it could be a rod bearing. The chances are pretty slim that you're gonna have what I had driving 75 MPH on I-70 coming back from Cruise Moab versus driving around the block, as far as throwing a rod into the side of the block. Again, a different time I had knocking that was my alternator, and taking the belt off confirmed that. My alternator was original, like yours.

Yeah I did that. And the knocking got worse... I had done a tuneup on it and then drove it to the mountains… And got home. I had been ridding my scooter around town and my nephew came into town and I took him out to red rocks in the 40 which I had not been driving. I did not check the oil it was more than a quart low when the knocking started less than a mile from home… I think when I filled it up with oil and just had it idling in the driveway the knocking appeared to go away but it did not.
Like I said I had the guys at Gunn Auto rebuild the head three years ago… The truck has been in the family since it was purchased I have no intent of selling it. I've actually been daily driving it for 10 years or more. I don't drive it as much in the summer because I use my scooter to jump around town.
I don't think that the engine has ever been out of the truck. And it's a 72. Not sure if I should just drop the pan and inspect what's going on down there… Or just pull the engine so I can fully inspect it. Other people told me to do the bottom half of the engine while I was doing the head but I could not afford to do so at the time and now I can and the weather is good.
But I don't know the specifics of how that even goes… Do I have to inspect the engine and completely dismantle it and take it to Gunn and then put it back together… or Do you take it over there with the Pistons and crank still in it? I have no idea of how that process works… It's not rocket science but I've never done that before.
Sorry about the confusion about the alternator it's definitely not the alternator or the water pump. And I'm pretty sure if it throws a bearing or something happens down there it damages the crank and needs to be resurfaced so that would involve a lot of things. Including maybe putting a new clutch on it just while the trans and tranny are off… I have thought I had had a rear main seal leak but I am more likely to think that the oil pan was leaking in the back. Not enough to even drop on the ground but visible on the housing below the clutch and had to replace one clutch so far. I don't think the oil pan gasket was installed properly. Sorry to be so lengthy about this I really appreciate your help Jeff!

 

[Capriblue45]

Gunn does not do any disassembly other than taking the old pistons off the rods so they can hang new pistons. You will need to tear it down to the bare block and then reassemble once they are done with the machine work.

 

[Rzeppa]

If you do decide to tear it down, the factory service manual is excellent, as is Haynes. If you see a Chilton's manual throw it in the bushes and then throw rocks after it.

 

[72 FJ40]

If you do decide to tear it down, the factory service manual is excellent, as is Haynes. If you see a Chilton's manual throw it in the bushes and then throw rocks after it.

Yes, I have both of them. I use them all the time. Kenny at Gunn said that they couldn’t get to it for a month after I dropped it off… Jeff do you see any advantage of dropping the oil pan and trying to figure out what is going on? Is it possible to fix it with the engine on… If it’s a main bearing or a rod bearing?

 

[Rzeppa]

A knock is almost always a rod bearing. Rod knock always gets louder when under load versus just sitting there idling. Dropping the pan won't hurt anything, just make sure you get the good OEM one piece cork gasket from the dealer rather the 4 piece aftermarket ones. When you go to put it on there are a couple tricks I've learned over the years.

Like I said above, that motor will drip drip drip for a long time. If it is a rod bearing and you do change it out without pulling the motor, you've bought yourself some time. Just be sure to plastigauge it before you button everything up to make sure your oil clearance is within spec. If it isn't, then yep, you gotta pull the motor and do the whole enchilada. It's not tricky, these vehicles were made to be serviced in remote locations with simple hand tools. I have a cherry picker and spare engine stand I'm not using at the moment you can borrow, I think I'm down to only one extra motor sitting around my garage (my wife says I'm a hoarder just because I have so many cruiser parts haha).

 

[72 FJ40]

A knock is almost always a rod bearing. Rod knock always gets louder when under load versus just sitting there idling. Dropping the pan won't hurt anything, just make sure you get the good OEM one piece cork gasket from the dealer rather the 4 piece aftermarket ones. When you go to put it on there are a couple tricks I've learned over the years.

Like I said above, that motor will drip drip drip for a long time. If it is a rod bearing and you do change it out without pulling the motor, you've bought yourself some time. Just be sure to plastigauge it before you button everything up to make sure your oil clearance is within spec. If it isn't, then yep, you gotta pull the motor and do the whole enchilada. It's not tricky, these vehicles were made to be serviced in remote locations with simple hand tools. I have a cherry picker and spare engine stand I'm not using at the moment you can borrow, I think I'm down to only one extra motor sitting around my garage (my wife says I'm a hoarder just because I have so many cruiser parts haha).

[EMBED content="thread-3788"]https://risingsun4x4club.org/xf/threads/2f-refresh.3788/[/EMBED]

I assume that this is a good thread for me to reference… Thanks again Jeff
David