I have searched many similar threads on here but none of them talk about a knocking sound along with fuel in the coolant. I am under the impression one of two things is causing the fuel/coolant mixture. Either a cracked injector cup or a cracked head. I have read about a few ways to check which cup it is.

The symptoms,

the knock sounds like a mini jackhammer thats really loud when motor is cold. As the motor gets to running temp it quiets down but doesnt go away. At high-way speeds/rpm or under heavy acceleration the knock is almost non-existant. Sooo my question is does a cracked injector cup also cause a knock?....possibly because of loss of compression in the cyclinder? Or would the knock be from something else? Remeber the knock gets quieter when motor gets warmed up and almost non-existant when at high rpms but returns when engine at idle or low speed. Your help is appreciated

 

They knock really bad when you have an injector tip broken too.

Blowing Grey smoke - YouTube

 

what may be happening is coolant is getting it the cylinder need to get it looked at it can bend a pushrod or worse

 

Fuel in the coolant is cup issue...99.995%...

 

The truck doesnt smoke at all so I dont think an injector tip is broken. It has a banks chip and still doesnt smoke.

I sure hope the knock is an injector related issue though. Anything else will be big bucks to fix. Ugh

 

Find the bad cylinder, remove injector, pressurize cooling system with hand pump, spray small amount soapy water into injector cup and look with flashlight for bubbles.

 

Please keep us posted on the repair.

Chet

 

I had fuel in my coolant and it was a cup. I didn't have the knock though, but I switched all my cups at the same time.

Once you get the valve covers off and buy the cups ,orings and rent the tool from Riff Raff you might as well change them all. Only one of my cups had an obvious crack but 6 of them had some discoloration which may have indicated the orings were going bad.

 

I agree, do all eight and be done with it.

 

there is an injector cup tool for sale he is asking 200 obo
7.3 injector cup tools!!! - PowerStrokeNation : Ford Powerstroke Diesel Forum

 

Yes do them all. Same with glow plugs etc..

Chet

 

Thanks for the advise. I took it took a couple different shops and they gave me a conservative estimate of about $1,000 to find the cylinder that has the leak and then replace the cup. Maybe it would be cheaper to just replace them all instead of spending the labor hours to test each cylinder. They also said the leak is probably causing the knock because I'm either losing compression or have excess fuel in the cylinder. I will probably take the truck to get fixed in the next week.

Why would i need to replace the glow plugs?

 

Your in there and they are cheap. Just make sure they don't charge you and arm and a leg to do a five minute per side job.

Chet