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1 month to 8.1 swap, then another month to Nv4500 swap

87 V20 Burb- 6.2 Diesel to 8.1-Th400 to Nv4500 I got around a month to complete, then a 800 mile drive. and then a 2300 mile roundtrip
I got the alt on, but then my belt wasn't fitting. I really like the Gate H/D series belts, but apparently they don't offer it in the extended length that I need it in. I got a std series belt, but I'll hold off for now on swapping it in.
 
Took another trip to my friends property. I loaded down the trailer and truck even more this time. Again, I had some warmer running temps while going up the steeper grades. I really want to try and address this. It seems like other guys haul heavier things and never hit 220-225. I’m running the big diesel radiator with the big 9 blade 8.1 fan. I put the delco t stat in it. I don’t think it’s that. One thing I did notice is that the fan stayed spinning for 10-12 seconds after shut down.

I do have a 16” electric pusher fan, but I think the mechanical fan should be up to the task. Does anyone know the temp in which the clutch locks up?

My plan is to start with a replacement fan clutch, and re-evaluate. I’ll be heading up to the same spot in a few weeks, so I’ll know then. Next step after that is a high flow water pump.

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I went to look at the fan clutch and see what I will need tool wise, and I seen this puddle under my Burb. It looks like I’ll be doing the water pump and fan clutch now.

I am relatively prepared when parts start failing, I made sure to do a once over on the engine when it was out. I took pictures of part numbers and casting numbers on anything I could see. The casting number on the water pump is #12558870. It crossed to a Gates pump that my work has in stock(#44089). When I looked it up by model, it was confirmed to fit a medium duty and g-series van with a 8.1.

I really wish that I had looked earlier today so that I could have gotten a flow cooler pump on order. They list it on their site for $189.00. So now comes the dilemma.

I can have the Gates pump, bypass hose, and coolant tomorrow. Or wait till Monday and see if Flowcooler has one in stock to ship out. Flow cooler is only a few hours south of me so if they have it, I should get it this week.


Dang it. Does anyone know if the pump can be removed without taking off other accessories?

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I went to look at the fan clutch and see what I will need tool wise, and I seen this puddle under my Burb. It looks like I’ll be doing the water pump and fan clutch now.

I am relatively prepared when parts start failing, I made sure to do a once over on the engine when it was out. I took pictures of part numbers and casting numbers on anything I could see. The casting number on the water pump is #12558870. It crossed to a Gates pump that my work has in stock(#44089). When I looked it up by model, it was confirmed to fit a medium duty and g-series van with a 8.1.

I really wish that I had looked earlier today so that I could have gotten a flow cooler pump on order. They list it on their site for $189.00. So now comes the dilemma.

I can have the Gates pump, bypass hose, and coolant tomorrow. Or wait till Monday and see if Flowcooler has one in stock to ship out. Flow cooler is only a few hours south of me so if they have it, I should get it this week.


Dang it. Does anyone know if the pump can be removed without taking off other accessories?

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Looks like you can leave the brackets on

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I decided to pass on the stock pump, so I’ll get in contact with Flowcooler tomorrow and get a water pump coming.

My transmission got dropped off in Stockton, so I took a trip out there and picked it up.

I got home and immediately my vehicular add kicked in.

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For those of you that were curious about the Vacuum brake rod retainer vs the Hydroboost rod retainer. Here is a few shots of the sheet metal bracket. I’ll get a new 4 pin switch and swap the assembly in.

I did this swap a few years back on another squarebody, but it had the dimples in the firewall for the clutch master cylinder and clutch pedal strut braces. My burb is a 87, which would have been a hydraulic clutch yr, but doesn’t have the dimples. Can anyone help with pictures or measurements of where they go?

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Oh, and during my ADD moment. I yanked out the column with the windows down.

who can tell me which wires to jump together to roll them up.

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One thing I did notice is that the fan stayed spinning for 10-12 seconds after shut down.

I do have a 16” electric pusher fan, but I think the mechanical fan should be up to the task. Does anyone know the temp in which the clutch locks up?
Just read through your build. Like it!

Didn't the replacement clutch make a big difference? If the engine is hot, the clutch should be fairly tight. Hot engine, off, there should be decent resistance to turn the fan. The stock 8.1L water pump should provide plenty of cooling with that big 6.2L radiator as long as you have a good clutch and fan. If the pusher fan is in front of the rad, it might actually be hurting. One thing I didn't see any information on is which shroud you're using and how well it fits to the fan. Have any pics? What was the old clutch out of? I guess there are CW and CCW types. I had cooling issues on my 6.0 (towing only) that were solved with a new HD clutch. The one that came on my 8.1 feels as least as stiff as that low mileage HD one.

Do you have a spare mechanical temp gauge to verify what the dash is showing? How about an IR temp gun? You could shine that on the engine inlet/outlet to see what the temp drop in the rad is.
 
Just read through your build. Like it!

Didn't the replacement clutch make a big difference? If the engine is hot, the clutch should be fairly tight. Hot engine, off, there should be decent resistance to turn the fan. The stock 8.1L water pump should provide plenty of cooling with that big 6.2L radiator as long as you have a good clutch and fan. If the pusher fan is in front of the rad, it might actually be hurting. One thing I didn't see any information on is which shroud you're using and how well it fits to the fan. Have any pics? What was the old clutch out of? I guess there are CW and CCW types. I had cooling issues on my 6.0 (towing only) that were solved with a new HD clutch. The one that came on my 8.1 feels as least as stiff as that low mileage HD one.

Do you have a spare mechanical temp gauge to verify what the dash is showing? How about an IR temp gun? You could shine that on the engine inlet/outlet to see what the temp drop in the rad is.




I didn't change the clutch out yet. When I went to look at what tools I needed, I noticed that the water pump was leaking. I figured I would change them both. The last time I ran it, the fan had very little resistance to it. It is a pusher fan, when you kick it on it actually helps the cooling and the ac. The old clutch was the original c3500hd unit with the 9 blade fan.

I am using the diesel squarebody fan shroud, it fits tight and has full coverage.
 
The rain hasn’t given me a break yet so the Burb is just waiting for me to get to it.

Since I had the dash out and some down time for the burb, I figured I’d change out this heater door selection bracket. It has been giving the signs that the tab might be busted. Low airflow to the defrost vents, and both the floor and dash vents blow at the same time. I removed the door flap vent cover and the tab is intact.
Are there any heater control gurus out there? I could use some help. The door flap doesn’t shut off the dash vents fully. It’s not quite shutting the door forward enough.

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The Flowcooler pump showed up next day. I had a slight hiccup when I ordered it over the phone. I told them I had a 8.1 from a van or medium duty truck. They gave me a price over the phone that was cheaper than what I was seeing on their site. The website didn’t have the part number easy to find, so I went with their lookup and placed the order. They sent me the confirmation email immediately and I saw that they were sending me the wrong one. A quick call back and it was corrected(at the higher price).

I have had a couple Flowcooler pumps. Most of them lasted me around 60-90k miles. I either sold the motor with the pump on it, or the entire vehicle. Flowcooler starts with a GMB brand casting pump and then works their magic. It sure doesn’t look like much, but function is more important to me than looks.

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I got a chance to look at my friends manual trans swapped burb. It’s a 90, and it was swapped from a th400 to sm465. I snapped a few pictures to give a reference.

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We finally got some decent weather so I squeezed in some time with the Burb. I got the transmission and t-case out today. I got all the cooler lines removed and took off the transmission gear selector linkage. When I finally got the transmission out. I found the source of the atf leak. It’s the electrical fitting for the kick down. Since I’ll be putting this transmission into another burb, I’ll need to address it. I assume it will involve dropping the pan to gain access to it.


My next step on the swap is going to be removing the flex plate and test fitting the flywheel. I hope to get the clutch hose figured out too. I’m using the squarebody clutch master cylinder with the ifs(non slave release bearing) slave cylinder.

I found the dimples for the clutch master cylinder and I hope to get those drilled out. I really hope to get the pedal assembly and master mounted into the burb this weekend.


Lastly(at the moment) does anybody have a master cylinder reservoir and mount? I can’t find one anywhere.

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I’m also trying to brainstorm some shifter boot ideas. I’ll most likely go with JB Fab’s setup for the 208/241 and the stock nv boot.

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Good news. The pump comes out easily.

but.. another fail. The original pump was definitely junk, but the new hi flow replacement is cast a bit thicker and didn’t clear the timing cover. No problem, a little bit of filing later, it fit. I go to put the pump on and find the gasket is torn.

Fine. I move onto the fan clutch. I start off with the wrong tool. A few stacked quarters and I got the clutch fan wrench to fit. I go to put the new one on, and the resistance is inconsistent. It free spins a half a rotation then tightens up. After a few hand spins it loosens up any almost free spins. Dam you Acdelco!!!

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The original pump was definitely junk, ...... I go to put the new one on, and the resistance is inconsistent. It free spins a half a rotation then tightens up. After a few hand spins it loosens up any almost free spins. Dam you Acdelco!!!
Why do you say the pump was junk? Wobbling on the shaft?

How you describe the clutch is just how my old one worked. It seemed to have some resistance initially, but after turning it by hand a bit, the resistance went to almost zero. Theoretically that could be a feature because it's better to have no fan at all until the engine warms up, but it's pretty hard to find any documented numbers of how much resistance there should be at various temperatures. Perhaps it's a sign fluid loss.
 
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