E250 5.8L Water Pump Shaft Broke - Now Idle Problem
 

Have a 1993 E250 5.8L. Water pump shaft broke, fan took out radiator and ended up jammed down near the lower hose under the crank pulley. Got it towed home, was able to start the engine and run for a minute or two to get the van parked. Figured leave it until the weather gets nicer!

Few weeks later had to move the truck again to turn it around, it started right up and ran beautifully for a minute, then the engine started racing, then died and wouldn't start again - stuck diagonally across the street, night, raining... Was eventually able to start by flooring it, and got it parked again with the engine racing (brakes work good).

Now it'll start but the idle hunts all over, if I give it gas it won't idle down.

I've got the new water pump, fan, clutch, radiator ready to replace, but wondering what caused the idle to go haywire. Could that fan jammed down there have hit the crank position sensor?

Does a visual inspection show any damage to the crank sensor? I can't help thinking something must have affected it----pretty much a miracle it runs at all.


Hope its nothing too serious though.

Well, first question is - does this engine have a crank sensor at all? Haynes book only shows a location for a V6 motor. Google search yields about equal "right side of harmonic balancer," "left side of harmonic balancer," and "no crank sensor, this engine uses a pickup in the distributor."

I agree with J W here, it sounds like something else was damaged when your shaft broke, and a tweaked crank sensor could cause erratic running. I think it's much more likely that it wouldn't run at all though in this case, and so it's possible that something else got whacked by your shredder once unleashed on your engine compartment.

Never heard of a shaft braking before though, any ideas how? Was there corrosion?

Never heard of a shaft braking before though, any ideas how? Was there corrosion?[/quote]

I'll know more once I get it out, but it looks like a plain old fatigue crack. The engine developed a low RPM vibration a few k miles before the event, which I was chasing thinking it was an ignition miss or vacuum leak. Assume now it was the fan/pully starting to wobble.

I'll be clearing away the air cleaner/grille/radiator later today and I'll be in a better position to look near the crank pulley. Also maybe shoot a few pics of the busted shaft.

Again, is there even a crank sensor on this engine?

Speaks for itself...

The fan clutch had failed, resulting in about 1/2" of slop - fan ran off balance causing the vibration I had. Eventually it fatigued the shaft. The result is rather spectacular.

https://www.ford-trucks.com/forums/p...ctureid=123605

https://www.ford-trucks.com/forums/p...ctureid=123606

No evidence of a crank position sensor down there, nor any damage to wiring - though there is a harness down there, it's well wrapped and looks undisturbed.

Wow...reps sent for the carnage pics!

Very interesting...:confused:

Wow----sorry 'bout that bad luck. :( Looks like the radiator suffered the brunt of damage, perhaps localizing it all saving any wiring etc below.

Once had a single blade of a five bladed metal fan clutch assembly develop a crack along the riveted mounting tang, vibrated somewhat softly, felt like a minor miss. ('76 Chevy small block motor) Eventually the small vibration loosened one of the four water pump bolts just enough to blow the gasket. Not a huge or costly repair but temps were below zero, this happened during a heavy snow forecast and the truck couldn't be driven off the freeway.

By the time my tow truck operator arrived the city had towed it to impound, citing the snow emergency, it was a potential hazard---I could pick it up anytime yada yada yada. Three days later, $280 in various costs (lot of money in '98!) the cracked fan and loose water pump bolt was finally discovered. Repair cost was under $1.00 (two water pump gaskets & on-hand fan clutch with blade assembly) excluding the second tow to a friends shop, temps still well below zero.

Long story short a vibration like this now has me looking until the source is found, experience shows its nothing good.

Agreed on the reps for carnage photos---mine on the way too!

This leaves the possibility that the TPS or IAC valve is the culprit for the idle problem. I don't like it, but I'll assume that the two symptoms (fan carnage and idle problem) are un-related and a coincidence.

Got water pump off. Only hitch was the lefthand most bolt (that has a pin that the power steering/AC pump bracket sits on) broke at the beginning of the threaded section, deep inside the aluminum cover on which the water pump mounts.

Question: pull off the aluminum front cover and try to drill out/re-tap the remains of this bolt, or install a threaded insert in the aluminum cover and bolt the water pump to that?

Any opinions?

The cooling system is all back together and working fine.

When I started the engine at first it raced like crazy and wouldn't settle down until I kicked the throttle a few times. Got it to idle sanely enough to top up the coolant and let the engine warm up. Eventually settled down to a fast idle - about 1500 rpm.

Figured it maybe needed an idle re-learn, so disconnected the battery and let it set for 10 minutes (but the engine was still warm), then started and let idle for 10 minutes. Idle never dropped - drove van around 10 or 15 miles, mixed town and highway, still idles around 1500, in gear it'll do 22mph without a foot on the gas. Engine runs smooth, good power. Just won't idle down properly.

Thoughts on what to try next? Try idle re-learn again? TPS? IAC?

IAC - Rocks!
 

Got Code 411 from EEC - Cannot control rpm during KOER low RPM check.

Pulled IAC and looky why... There was actually another one of those little rocks over on the other side of the plunger.

https://www.ford-trucks.com/forums/p...ctureid=126474

All Set
 

New IAC is in and the van runs fine. Idles right down under EEC control to about 600 rpm in drive. :D

Just wanted to say THANKS for following up with us and telling us how you fixed the problem. Never have seen rocks get into the IAC, was your air intake damaged by any chance?

Air cleaner is intact - but had been off for some time while I had the radiator and water pump out - those pebbles must have fallen into the intake hoses sometime while I had it all apart.

The original high idle event that prompted this post in the first place was before the air cleaner came off however, so must have had a different cause - low coolant level in the engine causing screwy feedback to the EEC... ? Strange.

Thanks all for the feedback and glad you enjoyed the pictures. That was about $600 worth of good times.