Massive over-rev, what should I look for as being broken? (1 Viewer)

[jgordon]

Well I'm an idiot, as has been documented at length here on mud. I installed a hand throttle cable the other day. I figured it was linked to engine rpm, and pulled up behind a truck, thinking I was going to pass. Truck coming the other way slowed down, first thing that went through my head was put in the clutch. Engine immediately went to like 5k rpm, stayed there for about 5 seconds.

Engine has gotten me about 1000 miles since then. I think I've lost maybe 1 mpg, and it sounds like I have some loose valves. Sounds a little diesely. Not making a huge racket. Is there anything I should check? Anything that will tell me or show me if I've buggered something up?

By the way, the dieseling I reported before was likely due to the exhaust leak from the gasket about to blow. It's stopped since I replaced the gasket.

Thanks for any quick replies.

 

[wngrog]

I had a hand throttle stick once on the trail and I put my 40 into a tree at 5000RPM. Toss that s***. Learn to drive 3 pedals with 2 feet.

It is probably fine, you think you hurt it, but most likely did not.

Change the oil and look for access metal in the oil.

Personally I would use Lucas oil additive that is thick like oil and a can of Sea Foam liquid in the oil as well.

Run it.

 

[mwalls54]

you just might have to adjust the valves. These are some tough old motors. i wouldn't think you hurt anything since you have gone 1000 miles. I would get a toyota hand throttle and mine only goes to 1800 rpm

 

[jgordon]

Thanks for the quick replies. It is a toyota throttle, off a diesel (maybe longer travel than the gassers?)

I agree they're tough. What also likely helps is the fact that the valves are vertical, rather than angled, meaning less chance of bending with piston contact.

I'm very glad to hear the thoughts. I'll take her home and baby her (valve adjustment, oil change (through a screen to check for metal) and generally talking sweet to her.

I guess if nothing else, I did learn that the 2F has a rev limiter. It's called valves.

 

[jgordon]

Learn to drive 3 pedals with 2 feet.

I'm definitely in agreement. I'm not sure if you saw my trip thread, but I've done 15,000 miles in 2 months. Aside from the idiocy, the hand throttle's been a welcome break doing almost 600 miles a day. In a wheeling situation, I wouldn't trust it either.

 

[GLTHFJ60]

I'm definitely in agreement. I'm not sure if you saw my trip thread, but I've done 15,000 miles in 2 months. Aside from the idiocy, the hand throttle's been a welcome break doing almost 600 miles a day. In a wheeling situation, I wouldn't trust it either.

I'm with mwalls on this one. I put a hand throttle in from a 62 ( a little longer ) and it won't hold my throttle high enough to go 65 down the highway, but it's good for some situations offroad. If I did it again, I don't think I would buy one, or if I did I would buy one for a 60.

 

[Trapper50cal]

Geez Jared,

I can't even imagine what 5k on a 2F sounds like...

I went to 3600-3700 and got worried by the sound.

That must have been eye opening to say the least.

 

[Mark W]

Personally I think driving with a hand throttle as a cruise control is foolish in the extreme.


5grand for 5 seconds should not hurt anything.... hopefully.

If it did... the first thing to let go are the rod bolts. On the exhaust stroke to intake stroke turnaround, they see their highest stress. The higher the rpm, the higher the stress. once their limit is reached, they stretch. They usually do not snap and fail immediately, but after stretching the nut will work loose... over stressing the other bolt too. Eventually while driving along, the nut vibrates off of one of the pair. The other bends and snaps. The rod cap separates on the downstroke to upstroke of the piston motion and the cap slams into the oil pan. It then rebounds up into the crank where it is thrown into and jams in between the crank/cam/block. The cam breaks in 4 pieces... the block skirt blows out. sometimes the crank tears the main bearing caps from the block. Lifters and pushrods fall into the pan.

Loud noise... engine locks and dies. Permanently


I have seen this happen in about a half dozen 2Fs. Not sure exactly what RPM they saw, but it was in the 6 grand and higher levels in the cases that I can pin down. I doubt that 5 grand did any damage at all.... I have always turned my 2Fs to 4500 when running through the gears hard and often take them to 5 grand for quick spikes. But just to keep you from relaxing too much how sure are you that it was only 5 grand? Surely you were not watching the tach at that point.... and I would not count on the factory tach to react quickly enough to show the true upper limit of any spike either.


Mark...

 

[Mace]

factory tach does not even hit 5k

 

[AKcruiserfreak]

Wow Jared! I don't even think my 2F would hit 5k. It would rev to about 4k and cry for mercy. These motors are resiliant.

BTW: Why did they move your trip thread? It sucks trying to find the expedition forum every time I want to catch up.

TK

 

[agent orange]

I know SBCs like to bend pushrods if you overrev them, if you find your valves are loose i might would pull the pushrod for that rocker and make sure its still straight (roll on flat surface, like a pool cue).

 

[Wile E Coyote]

Thanks for the quick replies. It is a toyota throttle, off a diesel (maybe longer travel than the gassers?)

I agree they're tough. What also likely helps is the fact that the valves are vertical, rather than angled, meaning less chance of bending with piston contact.

2f=No chance of valves ever hitting pistons (outside of one breaking and falling in)
And I hate to pile on, but I agree that a hand throttle does not a cruise control make.
I used to pull that stunt as a teenager in my Army days. 23k lbs of truck, Autobahn traffic, and a hand throttle.

 

[klinetime574]

You can rev up the 2F very fast if you are stuck in mud. I had pushed my redline a few times trying to get out of mud before my engine rebuild. We took apart the engine around 170K and it was just dirty. No bent pushrods or anything. All Hail 2F

 

[Hendrik]

... I would get a toyota hand throttle and mine only goes to 1800 rpm

I have an OEM diesel hand throttle on a HJ60 - also stops at about 2000 rpm. But its not really apples for apples, is it ?

Also very handy (and just a little dangerous) during PTO winch operation.

 

[RockDoc]

I've had my 3FE up to the redline (4500) a few times, and I'm pretty sure its been higher while not watching closely. I know it's not exactly the same bottom end, but I wouldn't be too concerned if nothing has made itself apparent after 1000 miles. I don't think you have anything to worry about from the top end. The valves don't open far enough for interference with the piston, and Mark has talked about taking rebuilds with stock springs up to 5500 or 6000.

 

[jgordon]

Personally I think driving with a hand throttle as a cruise control is foolish in the extreme.

Mark...

So when you say foolish in the extreme, is that with a little bit of admiration? Or the way it sounds?

factory tach does not even hit 5k

Yeah, the needle was on the "RPM" written on the tach. Not pleasant to hear or see. It all happened in slow motion though, giving me a lot of time to freak out and witness everything.

BTW: Why did they move your trip thread? It sucks trying to find the expedition forum every time I want to catch up.

TK

Curtis got it moved. Curtis, what the heck? Posting non-tech to my thread all nimbly bimbly.

 

[alaska60]

I hit 5k on mine daily! Oh wait............ its a 383 V8.
I ripped out my hand throttle the first time it stuck on me.
Jared,
you must be home by now... no?

 

[lehiguy]

Ok, here goes the hijack;

I worked at a Dodge dealership for years. A guy bought a new truck with a Cummins and immediately put in a performance chip. He had a turbo fail, which was the only one I ever heard of, but it was replaced in the shop. Well, when the turbo failed, the intake and intercooler partially filled with engine oil from the turbo that is pressure lubricated by the engine. When they put in the new turbo and fired it up, the RPM started to climb. The mechanic turned off the key, which shut off fuel to the engine, but that didn't stop it, is was feeding itself with engine oil from the intake and intercooler. It sounded like a jet plane before it finally locked up tight. A scan of the computer revealed that it hit 11,000 RPM before it quit. So, if a Cummins B series can do 11,000 RPM even for one second, your 2F can do 5,000 RPM without dying I'm sure.

 

[alaska60]

Ok, here goes the hijack;

I worked at a Dodge dealership for years. A guy bought a new truck with a Cummins and immediately put in a performance chip. He had a turbo fail, which was the only one I ever heard of, but it was replaced in the shop. Well, when the turbo failed, the intake and intercooler partially filled with engine oil from the turbo that is pressure lubricated by the engine. When they put in the new turbo and fired it up, the RPM started to climb. The mechanic turned off the key, which shut off fuel to the engine, but that didn't stop it, is was feeding itself with engine oil from the intake and intercooler. It sounded like a jet plane before it finally locked up tight. A scan of the computer revealed that it hit 11,000 RPM before it quit. So, if a Cummins B series can do 11,000 RPM even for one second, your 2F can do 5,000 RPM without dying I'm sure.

WOW! 11,000rpms. Thats nascar!
Not so highjacked as it kept to the thread.

 

[ntsqd]

Rare that a push-rod engine goes over 10k and lives. Most of the numbers that I've seen for a Cup car engine say 8k-9.5k depending on the track, though those are several years out of date now. The Boss 302 in a rear engine dragster that I used to crew on regularly went to 9-9.5k, but only for a moment!

Biggest worry to me in an over-rev would be parts that aren't supposed make contact, making contact. Unless it was a very soft hit, which from the description of the event I kind of doubt, you would know soon after that there was a problem.