A less conventional "GMT400": My '97 Express Conversion Van

[L31MaxExpress]

Finally one last improvement I made during maintaining the van. When my stock radiator cracked and started leaking, I flushed the system, swapped the stock thermostat for a 180°F and swapped the stock radiator for a 1-ton 454 or 8.1 core. The fan shroud did not quite cover the wider 34" radiator but it still cooled much better than the tiny, thin OEM core that is 31.5" wide. While I had it apart I robbed a van of the brackets and adapter for the engine oil cooler. The engine oil cooler lines and quick disconnects were replaced with GM AC Delco and plumbed into the 454 radiator. The oil pressure stabilized out and had nearly 10 psi more at hot idle. The load on these vans overheats the oil and cooks it.

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I used a 34x19 radiator with a 2-5/16" core on my 383 but the 34x17 is a better fit with the factory fan shroud. I had previously upgraded the trans cooler as well to help keep it cool.

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[L31MaxExpress]

Don't really know about the towing package on the Vans, but on the trucks it was not really related to axle ratio. It was more or less a factory towing hitch and transmission cooler, (maybe something else?) engine oil cooler? I believe. I think the 1500s trucks had 3.42/3.73 in that package though.

The trailering package was RPO code Z82 or Z85, can't remember which one.

According to the stock GM chart, axle ratio makes a HUGE difference in the tow rating. The 1/2 ton vans with 3.73 gears were rated a full 1,000 lbs more towing capacity than the 3.42 geared ones. 3.42 was like 5,500 lbs and the 3.73 was 6,500. Don't forget the weight of the conversion is not included in that and drops the rating signifigantly. On the 1-ton vans with a 454 or 8.1 the 3.42 gear option was 6,000 lbs towing and the 4.10s were 10,000 lbs tow rating. Then again GMs tow ratings were stupid too. A small block 350 1-ton van with a 4.10 gear was rated to tow almost 1,000 lbs less than a 1/2 ton with 3.73s despite the fact the 1-ton weighed less than 500 lbs more. Can download the information package with all the base vans specs on GM Heritage website in the Chevy Truck section. 96-02 are roughly all the same.

 

[zetros]

Wow! I appreciate all the information you've got for me. I think for now I'll focus on getting that 11 blade fan on (Is this a direct bolt on, and where would I get the fan clutch you have? I'm not the most well versed in working on vehicles, but I try to do my own work & teach myself), and doing the trans cooler upgrade writeup on this website, if you recommend that. I'll also look into getting a steeper rear end, this can get out of its own way fine but would be beneficial considering the conversion equipment + the hightop.

Not sure if I'll get to the 3/4 ton/1 ton suspension upgrade but I'll definitely consider it if I end up needing to tow more than I thought

I also had a question. I don't think any 4l60e can be slapped into any year truck, as the trans on my van was replaced before my ownership (bought it last December) 6 years ago under warranty. Would the shop just have used a "NOS" '97 4l60e or a 2015ish era one modified to work with mine? I doubt y'all would know for sure, as I can try and call the shop and ask them if they know. Was curious if this got a slightly revised 4l60e or not.

 

[zetros]

I also saw you were looking for shocks. KYB Monomax are what I used and they really work well controlling the heavy van without being too aggressive. My stock GM shocks were wasted at about 80K miles when I swapped them out.

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I'll give them a look. I was looking at some Bilsteins but really any good shocks will do, as I'm almost positive the stock ones are shot since it's been 23 years.

 

[L31MaxExpress]

Finally some of these vans cam with a 105a alternator despite having the conversion package. Alot of them also had a 124a or 140a CS-144 factory upgrade. I was easily able to swap a 200a AD-244 in place of my 140a CS-144. The factory harness had an added on pigtail conversion for the CS-144 that when removed allowed the stock harness to plug into the AD-244. Unbolted the rear alternator brace for the CS-144 and the AD-244 bolted right in place and reused the factory belt. My electrical system went from 12.5 volts with everything on to about 13.8-14 volts with everything on. AD-244 puts out alot more amperage at idle and is also more durable.

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[zetros]

Finally some of these vans cam with a 105a alternator despite having the conversion package. Alot of them also had a 124a or 140a CS-144 factory upgrade. I was easily able to swap a 200a AD-244 in place of my 140a CS-144. The factory harness had an added on pigtail conversion for the CS-144 that when removed allowed the stock harness to plug into the AD-244. Unbolted the rear alternator brace for the CS-144 and the AD-244 bolted right in place and reused the factory belt. My electrical system went from 12.5 volts with everything on to about 13.8-14 volts with everything on. AD-244 puts out alot more amperage at idle and is also more durable.

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That actually solves a concern I had. Mine has the 124 amp alternator and I was thinking about sticking a beefier unit on my truck, but looks like you've already got that covered. I'll add that to the to-do list on my onenote file on this thing's service history.

 

[L31MaxExpress]

Wow! I appreciate all the information you've got for me. I think for now I'll focus on getting that 11 blade fan on (Is this a direct bolt on, and where would I get the fan clutch you have? I'm not the most well versed in working on vehicles, but I try to do my own work & teach myself), and doing the trans cooler upgrade writeup on this website, if you recommend that. I'll also look into getting a steeper rear end, this can get out of its own way fine but would be beneficial considering the conversion equipment + the hightop.

Not sure if I'll get to the 3/4 ton/1 ton suspension upgrade but I'll definitely consider it if I end up needing to tow more than I thought

I also had a question. I don't think any 4l60e can be slapped into any year truck, as the trans on my van was replaced before my ownership (bought it last December) 6 years ago under warranty. Would the shop just have used a "NOS" '97 4l60e or a 2015ish era one modified to work with mine? I doubt y'all would know for sure, as I can try and call the shop and ask them if they know. Was curious if this got a slightly revised 4l60e or not.

Fan clutch can be found at a chain auto parts store like Oreilly or on RockAuto or Amazon. The factory style clutch can be had in severe duty thermal for the van and bolts right to that 11 blade fan.

Trans cooler is worth the upgrade time and effort.

Most likely it is a GM goodwrench or Serta remanufactured trans but hard to say for certain.

 

[L31MaxExpress]

This is the Hayden number for the clutch you are looking for. Should be able to cross it at any autoparts place and find the equivalent. Hayden or Four Seasons supply most of the fan clutches despite the name on the box. From memory most are manufactured by GMB. So most of them are just reboxes of reboxes regardless where you get them from. You can get an AC Delco clutch for a tow package Z82 vehicle, but it will set you back a little over $100.

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[L31MaxExpress]

One other little thing that drove me nuts on the GMT400 trucks and vans that is easily fixed. The stupid a/c cycling switch regardless who you bought it from would only last a year or two and fail leaving you without a/c. I replaced the switch with a r134a switch for a 94 G20 van and the matching connector. The 94 switch is adjustable and you can adjust the cutout pressure to just frost the accumulator before it cuts off the compressor, giving you colder air especially at highway speeds. With the older style switch I have been years without a single failure. The switch is on the accumulator next to the battery and removeable without losing your a/c charge because the port has a schrader valve. Spin it off and on quickly and you only lose a small puff of refrigerant but it was annoying having to bypass the switch and stop by an autoparts place mid roadtrip to get a replacement. Without the switch functioning the a/c evaporator freezes up every 10-15 miles and you have to switch to vent to thaw it out. I have used the older style switch on both my Express and 99 Tahoe.

 

[zetros]

One other little thing that drove me nuts on the GMT400 trucks and vans that is easily fixed. The stupid a/c cycling switch regardless who you bought it from would only last a year or two and fail leaving you without a/c. I replaced the switch with a r134a switch for a 94 G20 van and the matching connector. The 94 switch is adjustable and you can adjust the cutout pressure to just frost the accumulator before it cuts off the compressor, giving you colder air especially at highway speeds. With the older style switch I have been years without a single failure. The switch is on the accumulator next to the battery and removeable without losing your a/c charge because the port has a schrader valve. Spin it off and on quickly and you only lose a small puff of refrigerant but it was annoying having to bypass the switch and stop by an autoparts place mid roadtrip to get a replacement. Without the switch functioning the a/c evaporator freezes up every 10-15 miles and you have to switch to vent to thaw it out. I have used the older style switch on both my Express and 99 Tahoe.

The A/C compressor in my van was replaced very recently before I purchased it, but I'll look into doing that when I have the time.