CAVITATED 6.4L,,,for the 3rd time...ouch

[STROKER_T]

We got an '08 ambulance in,running hot,low on coolant,oil way overfull...pulled the water pump and WA-LA,front cover cavitation is evident.

2 times before at 6000 mile intervals this same ambulance was in for identical concern,this makes the 3rd visit,both times before replaced the water pump,front cover,and thermostats as recomended by ...WTF?

Any ideas on the repeat cavitation issues this vehicle is experiencing?

EGR cooler tests good(w/ hot plate)

[Mikill]

I don't think Ford even knows what's causing the cavitation. Me and another tech seem to believe it's more of an erosion concern due to too high of flow in the cooling system. But that's just a theory.

[Alex Bruene]

Running the engine with low coolant will speed up cavitation. I wonder if there is some other "coolant loss" issue that is contributing?

 

on edit: I say "speed up" instead of "cause", because I feel cavitation is inevitable on these things.

[LARRY BRUDZYNSKI]

Coolant flow won't cause cavitation....Aerated coolant will....I think if its watched more closely that we will find out that the coolant flow of this engine is causing aeration and in turn causing cavitation....My is that the coolant is passing a rather sharp edge and causing a bubbling effect in the area of concern and beating the hell out of it....I'm sure we have pics out there of the failures....Does this make any sense to anyone???? Picture this....Diesels vibrate and shake more than gassers, about 2-3 times as much. Aeration happens when coolant seperates from the entrapped oxygen molecules. The O2 molecules start bouncing off of every surface it comes in contact with and acts like ball bearings beating the walls and everything it comes in contact with. I have seen the class 8's 3406,60,N14 and others with cavitation concerns when not treated with the proper amount of a SCA or DCA, easy within 5-6 months after a in-chassis overhaul. We just submitted a claim with IPD for this very concern and was kicked back because the customer didn't add enough to protect the Detroit Series 60. 12853 miles and NO DCA, guess what not warranty....Does Ford add a additive package to their coolant to help with cavitation??????

[Keith Browning]

I forgot I wrote this for a second. Read THIS ARTICLE on Cavitation Erosion and the third paragraph explains cavitation and pumps. The answer here may simply be that the water pump in the 6.4L is either too big or coolant flow through the front cover is restricted. Perhaps the pump design is right at that critical edge where things like air in the system, low system pressure or high RPM's are just enough to create the conditions for cavitation to occur. Is a redesigned cover or maybe a larger diameter pulley to slow the pump down a wee bit the answer?

[gasgasman]

Great explanation Larry!

 

I read somewhere that when a boat's propeller cavitates, it is caused by the water boiling when it hits the surface of the prop.

 

Offshore oil drilling pipes suffer the same thing.

The ocean's currents causes eddys on the back side of the drill pipe causing some major errosion. They fix that by putting aero dynamic fairings on the drill pipe.

[STROKER_T]

They almost sent an "engineer" out to look at it...seems like the ambulances are most prone to such reoccurence,like was said with the high RPM,s possibly contributing...glad I asked about it,thanks guys!

[Fredsvt]

Oh great. I guess I'll know if high rpm will contribute to it.

Our shop's got a four 6.4s owned by an environmental company.

 

Two are F550 drill rigs, they're always complaining that the 20,000 lb rigs won't go over 85.

 

The other two, unfortunately idle almost continuously, as they power 5000 watt inverters to run water sampling equipment.

[Aaron]

^^^ 'member... 25 miles = 1 hour

 

4000hrs = 100,000mi.

[STROKER_T]

This pig got an oil cooler as well,some metal shavings in the oil and coolant,I'd bet money it'll be back like a boomerang is attached to it's ass....6.4's suk 2 work on in the cab

[rlchv70]

My understanding is that it is a combination of cavitation, and erosion/corrosion.

 

Any particles in the system will help to erode it. Have you done a good flush?

 

Any leaks in the system will exacerbate the condition. Does it hold pressure? How's the pressure cap?

[STROKER_T]

System has been flushed,holds good pressure,even road tested w/ pressure gauge,drove it hard,pressure never exceeded 11 psi....cap vents at 16...

Just a quick note,you are gonna love this...somebody in Detroit advised that we no longer use the rad-kit vacuum thingamobob to fill the cooling system on a 6.4,they seem to think it may be pulling the rubber off the t-stats....

This pig is out the door (for now)...

[GregKneupper]

I have a f450 tow truck that I have put 5 front covers on. They last about 7-10000 miles before it returns. Another guy here at the shop has their other tow truck that eats through covers as well. Our fse had told us that this is caused by the water pump pumping too much coolant and that the pump is actually causing negative pressure on the suction side of the pump. Supposedly they are still kicking around what they are going to do. He has informed me that they are looking at a few options like either adding some sort of restritor to slow it down of changing the size of the water pump pulley.

[STROKER_T]

sent us a proto-type front cover for this one...it's got a small bafffle welded at the bottom of the water pump cavity,kinda of a 1" X 1" plate,if you will....i can see where it would slow the whirling effect of the coolant...

[Keith Browning]

A picture would be most excellent!

[rlchv70]

Is the F-450 radiator the same as the F-350s?