I have a 89 k 2500 5.7 engine. It is on the 4 th radiator. I replaced the one row core with a 3 or 4 row core 43-1290 National radiator supercool or heatbuster series. The fan shroud hits the cores and has worn holes in each one. The radiators seem to be about 3/4 inch too long between the tanks to really fit the insulators at the top and bottom right. I ordered a new shroud and it is nothing like the original. On this one the shroud also holds the top of the radiator down. It hs both oil and trans coolers in the radiator. does anyone have any part numbers for the correct one???
First one the plastic tank split. the first two startd leaking at the seams in about a week. the third lasted 13 months before th shroud wore a hole in the core. the last one leaked within one day. I need a GM part number or somewhere to find the part number for the shroud. I ordered a new one yesterday received it today and it cannot work on this truck. It was bought new by my father in law. I would bet that the parts guy gave me one for a 99 instead of a 89
I would like to find a parts manual for this truck and eliminate this BS, but have not been able to find one..
The 89 thru 99 old style shroud should work because there was no real changes. The problem with 99's is that there are two of the (old a style and new) and some part numbers are confussing. Have you tried going to a dealer just to get the part number?
initially truck had OEM radiator and OEM shroud (Where the shroud holds the radiator)
Replaced radiator with "heat buster" radiator...had to trim shroud along the edges on bottom half to keep shroud from rubbing the core. THis should be obvious to you because you can't install the shroud unless you get really rough with the radiator, which I'm guessing caused your problems. I don't see how you could get the radiator to fit right at all without trimming the shroud.
Later I replaced that setup with a large be-cool radiator (sized for
3/4 ton truck) and I had to change the shroud because the OEM shroud whas too thin. I then changed the shrould to a 1998 version (based upon my reivew of a friends truck) 1998 K1500 350. THe shrouds on the
1998 are indeed thicker and require two additional mounts that hold the radiator. THe OEM shroud would not work because the be-cool radiator was too thick and too wide. Apparenlty the 98 year model trucks have a core about 19*34.
If you are going with a larger radiator than stock I would tell the parts guy you need a shroud for a 1998 K1500 and also the two top radiator mounts. Your radiator support already has the holes drilled for this, and you might pick up the 4 botls you'll need too, that the mounts attach to the core support with.
when I say the shroud was too thin... I"m talking about where the OEM shroud would not allow a "thicker" radiator to be installed becuase the shroud would interfer. THe 1998 shroud is quite a bit thicker in that it allows a larger radiator both in thickness and width to be installed. SInce you can't add space fwd of the radiator due to the condensor...you add space to the rear. So the 1998 shroud actually extends farther to the rear of the core support than did the OEM.
I think the 3/4 trucks may have the same setup...but I was not abel to look at a 3/4 truck at the time. I do know there is a difference between the shrouds that hold the radiator at the top mounts and the shrouds that require the two additional mounts I'm referring to.
On Thu, 20 Jul 2006 23:17:45 -0500, Elbert wrote: Lots of time people install a bigger raditor when improved airflow would cure the problem. GM Clutch fans age and engage at higher temps as they get older. Thye are easy to adjust though. I have a 89 4x4 burb that still has stock raditor and clutch fan 178K miles later. I have had to tweak the fan a few times as the bimetal coil controlling it does age but it still run cool and it never exceeds 210 in ANY conditions and it has seen 105 plus many times with A/C chilling. Sure a bigger raditor is nice but proper fan operation is important for best overall cooling and lower under hood temps too.
You can get a better fan. You can travel 100 mph (the air goes through the rad at the speed you travel.
I had a truck with a 2 core rad and a three blade fan. Replaced the fan and the thermostat but the telling day was when it rained and then stopped raining and I noticed a significant cooling effect with the cool rain on the rad. A three core rad fixed the problem for me. We were towing and the small rad wouldn't cut it. By the way, there isn't a fan on God's green earth that can suck air faster than the truck surging through the air at highway speeds. Stop & go, yes, highway NEVER.
You are quite mistaken here. A good engine driven fan can cool a engine better than ram air at highway speeds when needed. The air does not flow through the way you think becuse the is backpressure caused by the core stack and engine compartment too. I have a 2000 K3500 SRW with stock factory cooling with a factory 10 bladed fan on clutch. Recently when towing a loaded car hauler that weighed about 8K on a day when it was 95+. My engine never even hit 210 and A/C was chilling us and a few times on highway grades we could hear the fan engage for a bit because ram air did not cut it even at highway speeds. A proper engine fan will moved some serious air. Even my old 89 4x4 burb that I bought new will engage the fan sometime at highways speeds on really hot days for a little bit and it to has never been above 210 in it life and cooling system is stock towing package with aux tranny and engine oil cooler. Ram air cannot always be relied on to do the job.
Hotrodders have always known that you can remove the fan when you race. You only need it when the care isn't moving. Put it in gear Snowman, the fan isn't going to pull it and all the tweaking in the world isn't going to improve things.
Just look at what the factory does. They do NOT tweak the fan to make a heavy-duty truck. They add cores to the rad. I have never seen an exception to this.
The wear on the rad even happens with the old trucks. If you lubricate the rubber mounts with dishwashing detergent they will squeeze over the rad and allow you to mount it but over a short time will wear through, causing a lead on the tank I live in the Great White North of Northwestern Ontario and can tell you that a 2-core rad isn't enough unless it is just you and your lumch-pail, driving a few miles to work. Summer is much hatter in most any part of this continent than I'll ever experience and I have already determined this. Fans, praying to MECCA, I don't care. You literally HAVE to have surface area on the rad cores to transfer heat to the air. There is no substitute for a properly sized rad if you work your truck at all. If you tow, use overdrive for extended periods or haul heavy loads you should have a 3 or 4-core fan.
One guy at work told me that when the truck starts to overheat, to switch to second gear and watch the temp go down because the fan will be running faster and the engine will be working less hard in that RPM range. I did that and watched the gauge climb to the top in a few short miles, forcing me to pull over and idle it until cool. This is after changing the fan to a silicone nonsense fan with 5 blades and the thermostat to 180ºF Upon arriving home I searched the newsgroups and found that you need a larger rad than 2-core to drag a trailer on the highway. I bought a brand new 3-core rad and NEVER had that problem again.
Ask yourself this. Do you want to be at the side of the road, playing mosquito bait in my neck of the woods, on some God forsaken road, TWEAKING an old fan or do you want to be driving?
First hot rodders do not tow and keep heavy loads on engines for long periods of time so they can get by without a fan sometimes. They aslo do not use A/C generally which adds a lot of heat load to radiator core stack. Also you are mistaken because they do tweak clutch fans setting and the fans themselve with HD cooling systems (you have not done your research here) and even semis have fans that can engage at highway speeds because ram air does not always work plus when you are drafting or traveling with wind the ram air is greatly reduced. Postive forced airflow at times also lowers under hood temps which reduced heat stress on under hood components too extending the life of altenators and such. Sure you can use a 5 core radiator and try to get by on ram air but even if you did you under hood temps would be a lot higher than with a smaller radiatro core thickness and positive airflow. I run 7 PSI caps for long cooling system life with 70/30 antifreeze and my vehicles never even think about over heating in the worst of conditions with properly operating clutch fans. (my 89 with
178K has hoses that are still like new) Clutch fans also boost A/C output on hot day because they force airflow through condensor that cools refigerant more so that it can absorb more heat from cabin (this is why cars with electric fan force them one when A/C is selected). While you do not want too small a raditor for sure but nor do you want to be nieve enough to believe that ram air along can do the job all the time in a SUV and it will not do it towing on a hot day. GM had a lot of problems with Dmax's not cooling properly on hot days towing (no surprise given limited grill area and tight engine compartment they restricts air flow though it) so for year the got buy by saying temps of 230 or a bit more were "normal" towing with them and in 2006 they quietly greatly increased the size of the cooling fan and shroud and changed the calibration of it too to try to better control the problem.
Yes I agree with what you are saying but I don't recal anywhere in the OEM (GM) manuals where it talks about "adjusting" the fan clutch. At least I've never seen that documented, outside of your web site. I'm not saying you can't do it, I am saying that it is general practice to assume tha the fan clutch is either a pass or fail item, it either works properly or it needs replacement.
The regular radiator on a 1/2 ton of that year model is a piece of crap, and I'm guessing on the 3/4 tons too. The one I had was some 28 inches wide....compared to something like 34 inches wide for the heavy duty models which require a different shroud.
If you want to stay with OEM products and you verfity operation of the fan clutch and the cooling in inadaquate....if the shroud is fully operational and not cracked and the water pump is working..... you only really have one other items to look at, considering that the engine has no mechanical issues.
Its also woth nothing that the 34 inch wide model radiators are also thicker than the 28 inch wide modles. So in the end game you look for a radiator that presents the most surface area and has the laregest capactiy that your vehicle supports. Its obvious that on these vehciles from the 1/2 ton to the 3/4 ton and maybe even the 1 ton truck that they share the same front end, same radiator support and generally the same radiators and cooling system depending on the engine size and if it has HD cooling.
They only make one OEM fan for those year model trucks and the fan clutchs are designated by the rear end gearing (GM). So if you can't increase air flow you look to a larger capacity radiator or sometimes a more efficient radiator given a fixed surface area..
In my case I went with a large capacity / effecient aftermarket radiator that is roughly the same diminisons as the HD cooling model for the 3/4 ton truck. IN order to do so I had to change the shroud and also add the two top radiator mounts like the 3/4 trucks of that year have. Upon observation of a friends turck I did change the fan shroud to one like a 98 year model 1/2 ton because like i said previously it allows for a wider and thicker radiator install.
Of course its a given that if your truck is a 3/4 ton and came with HD cooling you most likely have all this in place to start with. But I'm guessing that some of the 3/4 tons with 350 engines had the crappy light duty 28 inch wide radiator, just like what was on my 1/2 ton.
I also think during this time some of the trucks had oil coolers built in the radiators while others did not, which I'm sure adds to the cooling issues.
I do think that the cooling on some of these trucks is marginal especially if you find yourself off road in 4 wheel drive where you have a situation of (hot summer days) low rpms and thus low air flow across the radiator. Situations where you are forced into moving slow. The truck is moving slow, the rpms are low and the temp is hot. A lot of these trucks run right around 210 all day long and you stress them much and they certainly will get aboove 210. SOmething parallel to heavy traffic on a hot summer day where you have a lot of idle time and repeated stop and go situaions. You can stress one oout on the hilly or mountionious areas too, given a heavy load and repeated stops up an extended grade (even on the pavement).
THe problems I've observed were most of the time situations where the truck did not or was not able to pull a sufficient amount of air across the radiator, due to the various situations you coud find yourself at extended idle time right in parallel with heavy loads on the engine.
I'm not talking about everyday driving on the interstate, or driving across town in light traffic.
I think even GM made note of this issue when they had some of these trucks with a auxillary electric radiator fan that was mounted on the front of the passenger side radiator and would come on and blow air across the passenger side radiator when I think the temp rose aboove approx 200. It may have come on in parallel with the A/C operation too?
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.