Gt3788 guys... a question

[tjsea]

So @laserjock I've kind of had a sudden thought come to mind. We talked the other day about your coolant filter and turbo returning to a separate port on your water pump. My thought was that with them in that extra port that too much coolant was bypassing the radiator and just circulating around in the engine. My thought to test the theory was to put a tee in the upper rad hose and return to there for testing purposes. Yes it will take longer to warm up initially, but it could prove my theory. So I'm laying in bed tonight (cause that's where all the best ideas come to mind lol) and thought this could also be the reason your fan clutch isn't kicking in. The fan clutch engages based off of radiator temp, but if the volume of hot water isn't making it to the radiator the fan clutch isn't going to kick in. In essence the engine is getting hot from circulating too much hot coolant within the engine and not making it to the radiator to be cooled off. This still doesn't answer the rpm based part, but to me it answers why your fan clutch isn't kicking in. Not as much volume of hot water through the rad = less heat being shed through the radiator and less hot air hitting the fan clutch to engage it.

 

[tjsea]

Btw just so everyone knows my truck is non intercooled. I am pulling water from the back of the head for the turbo and returning it to a tee in the heater hose going back to the water pump. My temps towing the camper to the rally were max of 210 when having it floored for a while getting on the on ramps. Otherwise it stayed at 200. Also mine is a 7.3, but it does have the 6.9l head gaskets with the corner plugs opened up.

 

[laserjock]

So @laserjock I've kind of had a sudden thought come to mind. We talked the other day about your coolant filter and turbo returning to a separate port on your water pump. My thought was that with them in that extra port that too much coolant was bypassing the radiator and just circulating around in the engine. My thought to test the theory was to put a tee in the upper rad hose and return to there for testing purposes. Yes it will take longer to warm up initially, but it could prove my theory. So I'm laying in bed tonight (cause that's where all the best ideas come to mind lol) and thought this could also be the reason your fan clutch isn't kicking in. The fan clutch engages based off of radiator temp, but if the volume of hot water isn't making it to the radiator the fan clutch isn't going to kick in. In essence the engine is getting hot from circulating too much hot coolant within the engine and not making it to the radiator to be cooled off. This still doesn't answer the rpm based part, but to me it answers why your fan clutch isn't kicking in. Not as much volume of hot water through the rad = less heat being shed through the radiator and less hot air hitting the fan clutch to engage it.

Yes! If you can decipher my ramblings above, I came to the same conclusion. I need to get a good measurement on my hose and either make or order an adapter.

 

[tjsea]

I thought you and I were on the same page, haha! This way everyone can see what the thought is. We have an old rad hose at the shop. I can cut it tomorrow and get you a true measurement.

 

[Macrobb]

Just to point out with the fan clutch:
The clutch engagement temp is different - by far - on "turbo IDI" fan clutch it's something like 205 ish; my turbo IDI fan(even years old) will engage quite a bit as soon as I go up a long hill, even empty.
The N/A IDI spec fan, on the other hand, doesn't engage until like 225 or higher. I rarely hear those engage.

 

[no mufflers]

do they have a different part number?

 

[Thewespaul]

I don’t believe so, but now that I think about it, that’s accurate to what I’ve seen as well.

 

[Agnem]

Keep in mind, that the water going to the turbo is primarily to prevent coking on shutdown. This turbo (and all others) are primarily oil cooled. The water moves through the turbo as if it were just another chunk of heater hose. There is no restriction, and no blockage, and in reality, the water stays in the turbo such a little amount of time, that it really has no opportunity to pick up additional heat load. It's when the engine shuts down, and the heat of the turbo performs a little bit of thermic siphoning to carry the heat just a foot away from the turbo or so that the water really matters. This is why the recommendation is to put it in-line with the heater core, as the cooling of that also helps the water move. Generally speaking, the water is only trying to take a few hundred degrees out of the turbo, so that it falls below 300 degrees reasonably fast, as it is the hotter temps that would turn the oil into a solid, and wreck those ball bearings in short order.

I'm not sure of the OP's plumbing, but possibly you have made a loop whereby a bit of coolant is recirculating without opportunity to go through the radiator?

 

[laserjock]

Keep in mind, that the water going to the turbo is primarily to prevent coking on shutdown. This turbo (and all others) are primarily oil cooled. The water moves through the turbo as if it were just another chunk of heater hose. There is no restriction, and no blockage, and in reality, the water stays in the turbo such a little amount of time, that it really has no opportunity to pick up additional heat load. It's when the engine shuts down, and the heat of the turbo performs a little bit of thermic siphoning to carry the heat just a foot away from the turbo or so that the water really matters. This is why the recommendation is to put it in-line with the heater core, as the cooling of that also helps the water move. Generally speaking, the water is only trying to take a few hundred degrees out of the turbo, so that it falls below 300 degrees reasonably fast, as it is the hotter temps that would turn the oil into a solid, and wreck those ball bearings in short order.

I'm not sure of the OP's plumbing, but possibly you have made a loop whereby a bit of coolant is recirculating without opportunity to go through the radiator?

I don’t think I’ve done anything crazy with the plumbing. I’ll see if I can sketch something up. All the water from the turbo and the heater core come together and go into the top of the water pump just like the heater hose would. Instead of pulling the supply from the heater hose, I pulled it from the back of the drivers side head.

I dunno. I ordered a top rad hose adapter last night.

At the rally @no mufflers showed me two fans he had. One I think he said was off a 93 or 94. It was quite a bit different. Maybe if he has time he can take a side by side pic.

 

[86.9]

Might be worth looking into a flowkooler water pump. I would recommend water wetter too.

 

[laserjock]

I’m running water wetter already.