Loud clank while driving

[guidoverduci]

I took the bronco out for a 20 minute drive. As I approached a stop sign, I heard this loud clank. I drove another few hundred fit and didn’t notice anything, but I decided to pull over and check it out. I left it running and poked my head underneath. I didn’t notice anything. The only thing I’ve done is install a relay for my electric fuel pump and wrap my exhaust because it’s really close to the fuel pump. I’m curious.. if the pump over heats, or shuts down, would the engine die?

After I shut the engine down, and then turned the ign switch to on, I couldn’t hear the electric pump. So I thought maybe it died. I felt the pump, but it wasn’t super hot, just slight lightly warm. The wrapped headers have about 1/4 inch clearance. I felt the wrap on the headers and it was hot, but not burning. Keep in mind, it was only a 20 minute drive. I decided to try and start it up (could swear I didn’t hear the pump at all...), and it fired up. I drove it 20 minutes home. No issues and pump sound is back when ign on. No idea what happened. I guess the bottom line is can the pump die and engine still run? And if the pump temporarily quit, could I restart it and then it starts working again once the engine is running?

 

[jedblake]

I've experienced 2 electric pumps die both were instant and never came back to life.
In regards to the clank maybe old motor mounts allowing the fan to contact the shroud; exhaust manifold/pipe loose, etc. Need more info on the rig and motor. Doesn't sound motor internal or top end or it would be constant.

 

[nickgp]

Check the following:
Driveshafts loose u bolts, worn u joints
Wheel lug nuts
Wheel bearings
Steering components
Shock absorbers
Exhaust system
Motor mounts

 

[guidoverduci]

I’m going to assume it won’t run if the pump dies, as in it will stumble to a stop. And it wouldn’t start again if was broke?

 

[SteveL]

Who knows what the clunk was. I had an electric pump too close to the exhaust on an old ch**y I owned. Even with wrap it would got too hot and vapor lock. Truck wouldn't die but would run real bad from lack of fuel. It was a cheap pump in installed as a temp fix. I think the better pumps like the Carter have less issues.

 

[DirtDonk]

I’m curious.. if the pump over heats, or shuts down, would the engine die?

If it dies, then yes the engine will stop after a short time because it's not getting fuel. How long the fuel in the carb lasts depends on if just idling (3 or 4 minutes maybe?) or driving up a long hill (20 to 30 seconds maybe?).

If it overheats, hard to tell what it will do. Sometimes they run fine when hot, other times they will not pump as efficiently. Still others it might die and not pump at all.
Like the carb bowl scenario though, how it runs depends on how it's running.;D
A hard run down the highway and a struggling pump probably can't keep up and your engine will sputter and maybe die. A slow city trip or idling in the driveway and you might not even notice.

After I shut the engine down, and then turned the ign switch to on, I couldn’t hear the electric pump. So I thought maybe it died.

How loud is it normally? Even normal running pumps don't always make the same amount of noise. But they are usually consistent enough that if you hear it one time you'll usually hear it the next. But not always...

I felt the pump, but it wasn’t super hot, just slight lightly warm.

That's a great sign. Means your exhaust wrap is doing it's job. Also likely means the pump was not sucking air or being overworked.

I decided to try and start it up (could swear I didn’t hear the pump at all...), and it fired up.

Goes back to the fact that fuel was in the carb even if the pump was not working. But the pump was working, because you were able to drive it for more than just a couple of minutes.
So might just be that inconsistency with the sound of the pump, rather than anything actually wrong.

I guess the bottom line is can the pump die and engine still run?

No. Not for more than a couple of minutes anyway.

And if the pump temporarily quit, could I restart it and then it starts working again once the engine is running?

Yes. But that would not have anything to do with the engine running. More to do with something electrical being loose, or an actual issue with the pump.
But for now, as long as it keeps the engine running I would not be overly concerned with the difference in sound.
Yet...

Paul

 

[guidoverduci]

Ok, I’ll rule out fuel pump for now. Gave a good visual inspection- I couldn’t find anything loose. I was curious about the driveshaft though. It’s the stock one with a 3.5” lift. As far as I can tell, it still works fine. What would be some signs I needed it extended?

Also, after I put the lift kit and new steering on, my caster is 2.1 and 1.7. I don’t notice anything while driving, but should I try to get those numbers higher with a drop bracket or extended arms? Sounds like the bottom line is to drive it again and see if I can track down / repeat that noise to get other ideas. Thanks!

 

[THEBONE]

Do you have a Detroit locker?

 

[guidoverduci]

Yes......

 

[THEBONE]

The locker will, on occasion, make a clanking sound, particularly when letting off the gas for things like a stop sign. It is not a regular occurrence, but does happen from time to time. At least mine does, I've been running one in my '76 thirty years.

 

[guidoverduci]

Man... if I had to guess a sound of that scenario, I’d say that about nailed it. I’ll give some more road tests and see if it happens again

 

[SteveL]

A friend of mine had a Detroit in his bronco. I would hear the loud clunk and chirp every time he pulled in.

 

[DirtDonk]

I'm one of the lucky ones, who's Detroit is totally silent. But it's not totally un-noticed however!%)
Roll around a corner with even a tiny bit of gas and the tires chirp. Drive in a straight line and every once in awhile you know you've got a locker in the rear of a short wheelbase high COG vehicle.
Lock a front hub now and then to lube the front end and it lets you know by throwing the steering wheel off-center and feels like it's trying to crab walk down the street.

But they sure have their purpose and place in life. Just not for most of us on the street.

Paul

 

[nickgp]

Good call on the Detroit locker making a clunk. First time I drove one it was extreme noticeable and unnerving.

 

[SteveL]

I'm still not convinced a Detroit in the rear is any better than just running a spool. At least a spool is consistent.