3FE CONNECTING ROD BEARING AND BOLT REPLACEMENT QUESTIONS (1 Viewer)

[Damen Brazen]

I’ve developed a light rod knock in my 1988 3FE and am going to change the rod bearings. The 260,000 mile motor has good compression (172-181 psi), good oil pressure, runs smoothly, doesn’t drink oil or smoke, and has no main bearing thump or noise on startup. I’m getting 13-14 on the highway at 55-60 mph and about 11 around town and it pulls strongly.

Since I only put 5,000 a year on it I'd be happy to go another five years without a major rebuild or engine swap.

I plan on replacing the full set of bearings with Clevite CB1440P with the engine in place, since the idea of pulling a half-ton, ten foot long, wire and vacuum hose encrusted engine/tranny combo out the nose of my FJ makes me just want to take a really long nap.

I’d like to also replace the rod bolts with ARP bolts; they don’t have a kit for the 3FE but my Toyota parts research says that it’s the same rod bolt used in the 22R. Unfortunately the rod bolts look like they are knurled for press-fitting.

So my questions are:

If anyone has experience replacing rod bearings on the 3FE, engine in place or not, what was your procedure, any tips/tricks?

Is it possible to change the rod bolts in place or do I need to remove the piston and rod assembly?

And finally what kind of oil clearance is acceptable in a motor that only needs to run another 20,000 miles or so?

I’ve had experience replacing rod bearings on an Oldsmobile V8. I was lucky in that it had a forged steel crank and the journals just needed a light cleanup with fine emory cloth. I will use Plastigague to check oil clearance.

Also, this is my first post. Thanks in advance for any advice you can give.

 

[cruisermatt]

Ok, good questions.

I'm sure you know this but for anyone else, if you hear a knock, do not run that engine anymore until you think you fixed it.

Ok, firstly I'll assume you know that it is a rod knock and not a stuck pushrod. [A stuck pushrod can make a very similar knocking noise. It will be a more consistent pitch where a rod knock will have two slightly different pitches (power stroke vs. exhaust stroke).]

You weren't asking this but the Clevite bearings will be fine, and skip the ARP rod bolts. Not needed and while not impossible, probably a mega pain to do under the rig. And not needed. The ARP rod bolts people use are from a Supra and require clearencing the bolt-head.

As for your actual questions.

1. Yes, I have replaced rod bearings with the motor in place. It's not any worse then doing a pan gasket job. Get a pair of the big 12-ton jack stands and put them under the frame so the axle is at full droop so you have more room to work.

2. Pull lower caps, use the rod to push the piston up a touch, replace bearings, pull piston back down with rod and re-install cap. Easy.
You can't remove the piston/rod with out taking either the cyl. head off or crankshaft out.

3. You want the same clearance as a new motor. 0.002-0.003". Skip the plastiguage and get a good mic. Assuming your crank and block are original they will most likely be STD size. There should be the sizes for the mains/rod journals stamped in the bottom of the block, and the code in the FSM, but you should double check with a mic. Measure the journal, if the bearing is the right size it will fit on the crank nicely. If not it won't and will be pretty obvious.

Hopefully your crank is still in decent shape so this works out for you. I have not been so lucky.
Also, welcome to Mud

 

[OSS]

for what it's worth, my 2F (which is very similar to the 3F) sometimes had a very noticeable knocking sound at idle even when it was only 2 years old with 40,000 miles on it (back in 1988). It sure sounded like some sort of rod knock to my uneducated ears but it would go away when the engine was driven. I drove it another 250,000 miles and 30 years like that and sometimes the knock was present and sometimes not at idle.

What I sort of figured the sound might have been (after 30 years) wasn't actually a bearing out of spec, (they weren't because I checked a few) but a slightly misfiring engine (when hot) at idle causing the engine to shake a bit laterally. I think I was hearing crank thrust noise (if there's such a thing).

Although your 3FE may indeed have rod knock, don't rule out the possibility that something else is causing that noise. 288,000 miles isn't a slam dunk for a worn out engine for the stout 3FE. If it never ran low on oil and iit was changed every so often, that engine can still go a lot farther

 

[Damen Brazen]

Thank you cruisermatt and OSS for your insights, they are very helpful.

I'll use a micrometer to check the journal size , not Plastigauge. Getting full droop on the front axle is an excellent tip. I saw those codes for bearings in the FSM, and it's good to know the correct oil clearance.

Sounds like changing the rod bolts in unnecessary, that's great news.

I have all the service records for the truck and it looks like the oil was changed every 3,000 - 5,000 miles. The previous owner said that he overheated the motor a couple of times, but he was not mechanically inclined. I noticed when I first got it that the fuel gauge and temp gauge would sometimes spike, so I cleaned the contacts of the voltage regulator in the fuel gauge. No more spikes. Hopefully the truck didn't actually overheat and it was just an erroneous gauge reading.

Looking at the head when adjusting the valves, I didn't see any cooked oil residue, but I did notice lots of sticky paraffin residue which I believe is the result of using Valvoline oil (which the service records indicate). I fought my OCD tendencies and left the residues in place, didn't want to dislodge a bunch of junk and have it in my oiling system.

I don't think it's a valvetrain problem due to the sound of the noise, the slight clacking from down below has indeed become a clack and a deeper thunk like that double knock you mentioned, cruisermatt. I guess I could pull spark plug wires one by one to isolate the bad cylinder(s) and listen for a change in the knocking sound.

As for other possible causes such as a misfire, I'll have to keep that in mind.

I am amazed that with so many miles I have such good cylinder pressure readings, it brings to mind the durable Mopar Slant Six.

 

[SteveH]

The advice you have gotten here (and your plans) all sound good. I replaced the rod bearings (one was badly worn and knocking) on a '58 Massey Ferguson tractor whose engine had been rebuilt in 1976, and simply slipped in the new bearings without issue, as described above. When I studied the bearing shells, they were oversize and date-coded 1976, so don't order bearings until you see if someone has already been 'in there' and done some work. I had 2 feet of clearance under the engine, but the oil pan is cast iron and tied into the front axle, so it was an adventure to fix.

On my tractor, the oil bypass valve had stuck open (due to varnish) and so the engine had been running on super-low oil pressure for many years, which took out the oil-starved bearing. With the new bearings and fixed oil valve, I have 60 psi cold, 40 hot oil pressure. I have driven it another 10 years, and it's worked perfectly. The crank survived the abuse.

I might still use Plastigage, along with any other measuring techniques, but having used it, you have to be careful how you use and it how you interpret the results.

 

[cruisermatt]

I don't think it's a valvetrain problem due to the sound of the noise, the slight clacking from down below has indeed become a clack and a deeper thunk like that double knock you mentioned, cruisermatt. I guess I could pull spark plug wires one by one to isolate the bad cylinder(s) and listen for a change in the knocking sound.

With that information I'd just go ahead and pull the oil pan now. I'd take a guess that it's probably leaking anyways. I wouldn't risk damaging the crank by running that engine any more.

 

[Damen Brazen]

Thanks again to everyone for their input. I liked your story about the tractor, SteveH.

I changed out the rod bearings yesterday, drooping the front axle to get access to the oil pan. It was pretty straightforward, taking about 6 hours to do. The shells came out easily enough, with a couple upper ones dropping out as soon as I pushed the piston and rod assembly up off the crank.

The bearing shells exhibited even wear, with a couple pairs showing light scoring and a few corrosion pits. The inner surfaces were just beginning to change color to what I assume is the backing substrate of the shell.

The crank pin journals were smooth and didn’t catch a fingernail dragged across the surface. One forward journal (number two, the one making all the noise) showed slight discoloring (oil residue) in a bar pattern which I lightly cleaned off using a bit of emory cloth.
The forward three crank pin journals showed more wear than the back three, I am guessing this has something to do with either oiling or cooling favoring the back cylinders. Using Plastigauge (forgive me, CruiserMatt!), I recorded 0.038mm oil clearance on cylinders 1-3 and 0.025mm on 4-6 with the new bearings. This falls within the acceptable range in the Field Service Manual of 0.020mm to 0.050mm. Seeing that I only put 5,000 miles a year on her, I am planning on a full rebuild in about five years.

Getting the cork FelPro oil pan gaskets in place was a bit difficult. I cut the end tabs off the long side gaskets so that they would mate more easily with the front and back short gaskets. I used RTV Ultra black to glue the gaskets to the engine and to plug the corners where the gaskets meet, and a light coat of spray on gasket sealer on the pan side. I went easy on the RTV and spray since I wanted the cork to get oil and swell to seal as it is designed to do, and to be able to get the pan off in the future without cursing. No leaks, yet…

 

[cruisermatt]

I don’t see anything that would cause a rod knock... is it still making noise?

 

[Damen Brazen]

The dull double knock clacking/clunking noise is gone, as is much of the general clattering from the bottom end. It seems to run more smoothly at higher RPMs than before, but I'm not sure if that's a psychological effect (like when you change the oil and it seems the truck runs better, although science says that isn't so).

And to be clear about what I assumed was the rod bearing noise, I noticed it increasing in volume and changing over the last 5,000 miles. It was really noticeable at cold idle. It never reached the stage where you would hear it driving by and say, "Oh boy, that guy's gonna toss a rod through the block," but it did get to the stage where you could hear it hot or cold at any engine speed.

There is still a considerable amount of tapping noise from the lower part of the motor. Other FJs I've heard in person and on these forums seem to make alot of mechanical noise, some much more than mine, so I'm not sure if it is a problem.

I know that the solid valvetrain can be a cause of noise, but besides one tapping noise, it's quiet at the valve cover. Could it be that out of adjustment valves make more noise at the camshaft/lifter than they do at the rocker arm? And since you seem to be quite expert with this motor, is there any special trick to adjustment? I simply followed the FSM. The only other thing I can think of is perhaps the lifters or the lifter bores are worn.

 

[SteveH]

Those bearings look good for the number of miles. Thanks for posting all the pix and info. The 3F-E is a noisy engine (even with valves adjusted and in good shape) compared to anything newer!