PLUG ON TOP OF WATER PUMP USE??

[MikeyD]

Hey all, I have a 1990 7.3 IDI F-250 and I’m doing a coolant flush for the first time. I drained the engine block without considering how to refill it (without removal of thermostat), and I noticed a plug (see pic below) on top of my water pump...does anyone know what this is for? And what I’m getting at is - is it possible to fill the block directly going through this? Or is the only way to fill the engine block to go through the thermostat housing?

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[chris142]

Different vehicles use different heater hose setups. That plug would be used if the engine was in a different application. As for filling it up.just pour into the radiator.

 

[MikeyD]

Different vehicles use different heater hose setups. That plug would be used if the engine was in a different application. As for filling it up.just pour into the radiator.

If I just pour into radiator, won’t the engine burn up because there’s no fluid inside to pressurize the thermostat to open and allow more to flow in?

 

[MikeyD]

Different vehicles use different heater hose setups. That plug would be used if the engine was in a different application. As for filling it up.just pour into the radiator.

And because it’s an option for a different hose set up...does that mean I CAN fill coolant through this hole to get the block full?

 

[Thewespaul]

No, there is a check ball in the thermostat housing that allows bypass to eliminate air pockets. That port is most often used in school buses and ambulances

 

[Thewespaul]

And because it’s an option for a different hose set up...does that mean I CAN fill coolant through this hole to get the block full?

You could, but you’re really making this more difficult for yourself than it needs to be.

 

[MikeyD]

I ask because I tried the radiator fill but it only took 3 gallons and after 45 (I know...probably way too long...) minutes the thermostat never opened and I caught my temp gauge spike wat overboard...turned off the truck immediately. Hoping I haven’t done irreversible damage already that’s why I want to fill the block directly...so it doesn’t run dry again. Does that make sense?

 

[MikeyD]

You could, but you’re really making this more difficult for yourself than it needs to be.

I ask because I tried the radiator fill but it only took 3 gallons and after 45 (I know...probably way too long...) minutes the thermostat never opened and I caught my temp gauge spike wat overboard...turned off the truck immediately. Hoping I haven’t done irreversible damage already that’s why I want to fill the block directly...so it doesn’t run dry again. Does that make sense?

 

[Macrobb]

Honestly, do yourself a favor. Pull the thermostat housing. Replace the thermostat - it may well be bad anyway. While in there, find the check ball in the upper housing and remove it completely. You now have a 1/4" diameter bypass for air when filling - no more bleeding or waiting for it to drain down.
It doesn't seem to affect warmup time at all.

Make sure to use a genuine Motorcraft thermostat. The other ones like to break and don't fit quite right.

 

[genscripter]

Yeah, the OP is overthinking this. By filling the radiator, you are filling the lower rad hose. That hose is connected to the block, and when fluid flows into that chamber, it works its way up as the water level rises in the radiator. Even with the check valve, the coolant system isn't 100% air-tight, so given enough time, the block is always somewhat full of water, just as long at the radiator is full.

It will overheat a little when refiling after a coolant flush or t-stat replacement or waterpump replacement. And unless you have a heater core block-off valve (like in the rear circuits on the van), you will always have some coolant flow out of the block to the heater core circuit to help siphon off the heat of the block even with a theoretical blocked t-stat.

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That is especially the case when the vehicle is idling and not under load. So it would be really hard to cause major damage to an idling IDI with a supposed blocked T-stat or block with several pockets of air in the coolant systme.

That being said, I would definitely replace the t-stat with a motorcraft t-stat like Mac said. Wince you are already doing the work on the waterpump, it seems natural to install the t-stat too. Also, buy a 2nd t-stat and put it in your glove-box, just in case you run into heating problems a few years down the road.

 

[icanfixall]

Honestly you are WAY over thinking this. Do this really simple suggestion. Remove the heater hose from either the head connection or the heater core at the firewall. then as you refill the engine this allows trapped air to escape. My thoughts are no damage was done and your thermostat air vent ball is not checking correctly.
As for this plug in the top of the water pump..No worries there. this pump is designed for many other rigs. This port will be used to cool a air compressor on some trucks and bus applications. Those air compressors also have a pressure fed oil system from the drivers side main oil galley oil ports behind the oil cooler bundle.
A reason you might only get half the coolant back in the engine is you did not drain the block from the side drains.

 

[IDIBRONCO]

Also, just because your temp gauge may say that it's hot, it's not really overheating unless there's coolant being pushed back out of the radiator overflow.

 

[Macrobb]

unless there's coolant being pushed back out of the radiator overflow.

For anyone else reading this topic, if this happens when it's *not* extremely hot, it's a blown head gasket.

 

[genscripter]

Also, if you did the Waterpump job on an IDI, you need to permatex the right bolts: http://www.nickpisca.com/diesel/engine/which-bolts-to-permatex-on-a-6-9-7-3-idi-waterpump/

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[chillman88]

Here's my question.

When you put the three gallons in did you leave the cap off and top it off or did you cap it and run it?

You should leave the radiator cap off and start the engine. As the engine runs your level will go down (air escaping) and you need to top it off as this happens. You'll lose a little bit of coolant as occasionally the level will rise a little too. When its fully warmed up cap it, shut it off, and call it good.