Here is a quik question in the 7.3 thermostat housing there is a bypass port and it has a little steel ball in it. how does the bypass work and is that steel ball suposed to stay in the housing port only or is it suposed to move freely from housing to block?
Thank for your help

 

The little ball is the air/vapour vent bleed. The diesel thermostats do not have an integral air bleed like most automotive thermostats and that is on of the reasons why it is best to stick with OEM rather than aftermarket thermostats when replacing.

It has been a while since I did mine on my 93', but I believe the ball is held into the block by a little plastic bushing. I could be wrong on this.

If you got your thermostat out check if it has a rubberized heat shrunk copper ring on the outside of the housing. If it does, replace it with a newer model. The copper ring on a 92 i worked on once broke and kept sliding on the housing blocking the cooling water flow intermittently. This lead to a very frustrating intermittent overheating problem as the ring would slide some times and not other times and would always reseat when the engine cools down.

I believe the intent of the ring was to provide better thermostat sealing to allow the engine to warm up quicker by eliminating too much coolant leaking past the thermostat housing when the thermostat is closed.
As I said, stick with an OEM thermostat. The extra $10 are worth it.

 

When I removed the housing the part that the radiator hose connects to the steel ball was held into that part but the plastic bushing was breaking apart. if that ball was removed would it resalt in the eng. running to warm or to cool? and as for the thermostat its self I replaced that with a new one oem. the local dealer wanted 35.00 I got thru rockauto for 23.00 deliverd.

 

Without the ball check valve you may be getting too much bypass and your engine may start to cool down (i.e. not stay at normal engine temperature) on cold days during idling or light driving.

This is probably not the end of the world but may have some impact on fuel economy as the truck will take longer to warm up to normal engine temperature after cold starts.

Without the ball and the coolant passing thru the hole, the concern would be overcooling not overheating.

 

Thanks for that. I use my truck mostly for pulling my fifthwheel, and it tends to run warm. I still need to know if that ball is to move freely from eng. to thermosat housing or locks to one or the other.

 

The steal ball moves freely in the housing, it does not lock into the block, the way to check to see if its free, with the engine off squeeze the upper hose and you will hear it move arround. if the ball fell out i would replace the housing. i would be worried that the coolent would run too fast through the block and creating hot spots

 

I left the ball in the port it is moving freely from eng. and housing I checked the port on the eng. and the ball cant get sucked thru I have two heat gauges the factory and I put a mechanical one in. the temp is running between 192and 198. I will keep a close eye on it and if it looks like it will be a problem I will replace the housing. (the real test will be in two weeks when I pull the trailer on a short road trip.)
Thank you all for your help.

 

Sounds like everything is aok.

Sadly the time you find out if your radiator still has enough cooling capacity and is not fouled too much is when you are under heavy load.

You should be in good shape with the mechanical temp gauge you installed.


Best of luck.....

Seb.....

 

Well I went on my mini vacation I ended up going to the cost instead of orgon. I hooked up my fifthwheel and packed the family and headed south for ventura beach and all whent well until I hit the grapevine 6% grade 5 miles long. with in the first mile my temp shot up tp 225. I had to pull over three times to make it to the top.then it ran fine the rest of the way. coming back home I took the costal route the grades are not as long or as steep. we left at 430am so it was nice and cool. my truck did get up to 215 at one point. but it was just for a moment most of the way back it ran from 205 to 210. I had to order the thermostate housing from rock auto the local parts house could not get it.I put the new housing on and packed the trailer, family and headed for monteray the truck ran just the way it should 195 to 205.
So any one having a heat problem before you replace the radiator, fan clutch water pump. start out simple change out the termostate with a factory one and and change that thermostate housing it only coast $25.00 delivard. It just might save you alot of greef and alot of money.

Thank You and God Bless everyone for there help