'76 K10 400 Small Block Fan Shroud

[nabeshin]

My 400 has the BBC radiator. Siamesed cylinders need more cooling capacity, it seems. Has the trans cooler on the side below the cap.

My shroud is one piece though. It might not be original. Seems to fit poorly cause it is warped.

I had to have my radiator fully rebuilt since it was corroded internally and plugged with gunk. That all came loose and leaked when I flushed it. The rebuilder couldn't plug all the holes and still provide cooling so a new core was needed.

The truck moved regularly since it's retirement in the mid 2000s, but essentially sat that whole time. So the coolant was no longer preventing corrosion.

 

[legopnuematic]

My 400 has the BBC radiator. Siamesed cylinders need more cooling capacity, it seems. Has the trans cooler on the side below the cap.

My shroud is one piece though. It might not be original. Seems to fit poorly cause it is warped.

I had to have my radiator fully rebuilt since it was corroded internally and plugged with gunk. That all came loose and leaked when I flushed it. The rebuilder couldn't plug all the holes and still provide cooling so a new core was needed.

The truck moved regularly since it's retirement in the mid 2000s, but essentially sat that whole time. So the coolant was no longer preventing corrosion.

My fan shroud I'm using on my 79 is from my friends 75 k5 that had a 400 in it, it is a one piece shroud.

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Sent from my Moto Z (2) using Tapatalk

 

[AuroraGirl]

My 400 has the BBC radiator. Siamesed cylinders need more cooling capacity, it seems. Has the trans cooler on the side below the cap.

My shroud is one piece though. It might not be original. Seems to fit poorly cause it is warped.

I had to have my radiator fully rebuilt since it was corroded internally and plugged with gunk. That all came loose and leaked when I flushed it. The rebuilder couldn't plug all the holes and still provide cooling so a new core was needed.

The truck moved regularly since it's retirement in the mid 2000s, but essentially sat that whole time. So the coolant was no longer preventing corrosion.

My fan shroud I'm using on my 79 is from my friends 75 k5 that had a 400 in it, it is a one piece shroud.

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Sent from my Moto Z (2) using Tapatalk

my dads 75 with 400 has a 2 piece... but not up and down. its like 2 piece where the first one barely clears the fan and then a top trim piece iirc?? that extends over past the fan? Looks like yours but there was another

 

[CmdrShepard]

I guess I would say this, without at least a fan, better yet a fan and shroud it's hard to know if there really is a problem or not. Could be an air pocket like Wayne said, it could be a problem with a head gasket, you said it sat long enough for the engine to be stuck a bit, that's certainly long enough for corrosion to occur.

I think I'd fire it up with the radiator cap off and see if it starts pushing coolant out right away, if not I'd at least get some way to tell coolant temperature. If you have a harbor frieght in your area you can get a IR heat gun for about $10. Then a fan on it or setup a box fan in front of the radiator to maintain air flow and run it a bit see what happens. Take temp readings at the thermostat housing and the top and bottom of the radiator.

Thanks for the info. I finally received the coolant sensor that I ordered and installed it, but it looks like my gauge went bad as well or there is a wiring/connection issue somewhere that I'll need to track down at a later date. I think I will get the IR thermometer just to double check, but since I reinstalled the fan I haven't had any obvious overheating issues as far as you can tell without a way to actually measure the temperature. I have run it with the cap off and coolant is circulating and there are no signs of a blown head gasket (no bubbles, no oil/fuel in the coolant, no sign on the plugs, and no white smoke). It's possible it was just from idling without the fan that first day I had it running again.

 

[CmdrShepard]

I6,small blocks besides 400 got the one on top. 400's and 454's got the larger radiator, which uses the one on the bottom.

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If along the top of the core support those 4 holes have threaded inserts in them, it had the largest radiator option. A little hard to see but this core support is off of a 79 GMC K25 that had a 400sb in it.

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Any chance you know if the core support is drastically different between the two options? From what I'm reading here I believe it is a 350 radiator and the upper mount resembles the top image in your comment and my radiator is not flush with the top of the core support. I have a guy who is willing to give me a BB shroud and mounting brackets/top plate for free so all I would potentially only need the larger radiator, but I don't know if this is just a drop-in item or if I will need to do a little fab work to get it to fit.

 

[SirRobyn0]

Thanks for the info. I finally received the coolant sensor that I ordered and installed it, but it looks like my gauge went bad as well or there is a wiring/connection issue somewhere that I'll need to track down at a later date. I think I will get the IR thermometer just to double check, but since I reinstalled the fan I haven't had any obvious overheating issues as far as you can tell without a way to actually measure the temperature. I have run it with the cap off and coolant is circulating and there are no signs of a blown head gasket (no bubbles, no oil/fuel in the coolant, no sign on the plugs, and no white smoke). It's possible it was just from idling without the fan that first day I had it running again.

Perhaps more time passed during that first run that you thought. I know for me sometimes when doing something like that, your checking this and that, and watching things next thing you know a far bit of time has passed.