Radiator Blocking for Winter Conditions
 

My vehicle is a Sierra P/U with the 4.3L engine. Over the past couple of winters here in NW Indiana I've ran with the radiator 85% blocked. My crude, but effective technique is to put cardboard between the the A/C coils and the radiator because of the ease of adding and removing same. This summer I ran with the radiator 80% blocked without any problems. I'm considering using a 90-95% blocking of the radiator for the winter. I'd like to hear from folks in the northern climes about their blocking techniques, materials used, tips and tricks.

I had the radiator in my 98 Sierra with the 5.7 L V-8 95% blocked with no problems. The a/c was a little weak (but still usable) on 100 degree days. I ended up ripping it out because I was going on a road trip on a very hot day and I wanted the A/C (and transmission cooler) to be at its best. I'll probably put it back in sometime in the next month or so.

EDIT: I forgot to put a link to my grille block:

https://www.gassavers.org/showthread.php?t=8927

I ran 100% block on my 2002 Sierra 5.3 with the same technique as you, having cardboard (actually I used corrugated plastic, similar but weather-resistant) wedged between the engine's radiator and the A/C stuff. I tried it for a while in varied weather, ranging from warm to cold. It was fine.

I eventually made a nice cover for the front of the grille to force the air around the truck instead of letting it past the grille at all. It worked great except my transmission temperature went way up, so I eventually took it off. I think this winter I'm going to put the coroplast back in front of the radiator.

What distances are you guys driving? I had a 24 mile commute each way to work before I moved to New Mexico and when I tried a 50% block between the AC and radiator my mechanical fan clutch started stiffening up all the time and the losses from a fan pulling against a blocked radiator as hard as it could ruined my mileage.

38 miles to work, 40% freeway (set the cruise control at 65-70mph) and the rest a combination of town and country roads. I don't know how to tell if my fan (also a clutch fan) is running all the time, but my fuel economy was not measurably affected. My temperature never rose above normal, and that temperature gauge is quite dependable.

If it is a good clutch, which I imagine in a 2002 it is, you'd hear it. The Durango's fan has a super duty clutch on it from the factory and when that thing stiffens up you know it. With it at full hold I can't rev past 3000 without the belt starting to slip, and that's with a good belt! It only really does that around town with the ac on or when I'm off road though.

I tried to rev it up with the hood open while the clutch was hot like that and I couldn't do it. The level of heat coming from that system is unbearable.

ne other suggestion I have is to throw a piece of cardboard over the engine to act as an engine "snuggie". The idea is to help insulate the engine aiding in quicker warm-ups, and preserve engine heat a bit longer when you're running errands with multiple stops.

I have no proof that this actually helps. but when it's -20 outside, it can't hurt.

That would probably be too much of a fire risk. Besides, most cars already have fiberglass insulation on the bottom of the hood.

The only way this could happen is if you tightly wrap the exhaust headers in it. Cardboard burns at around 500 degrees. Your thermostat is set at 195.

Even if there isn't a fire risk,(Which I still think there is) I don't think there is going to be any noticeable difference in mileage.

-Jay

Well, if it catches fire that'd help the warmup some!

I can see it helping with fuel economy, but I think there's more risk than it just catching fire from being hot. I'm not exactly sure what but I won't be trying it.

Just throw some fiberglass batting over the engine if you want more insulation.

Aren't your thermostats operational?
I've had t-stats that were stuck open. In those situations restricting the air flow through the rad worked because restricting the coolant flow through the rad wasn't working.

I can see a hot water tank blanket or foil lined fiberglass as an engine blanket to limit the block's surface area from acting to radiate heat, but blocking the air through the rad??? Fix the t-stat!

:eek: I had a GM Service Manager jump all over me for blocking air flow.
Told me something along the lines of; the engineers are pretty good at what they do and that they know their product will be driven in winter and design accordingly and they even test them in all conditions........

Auto manufacturers' engineers are some of the best in the world; those companies have the budget, prestige, pervasiveness, and benefits required to attract them. It can be tough to out-engineer them at home.

However, we have different priorities. Things we do like this are customizing, not necessarily better engineering, just reconfiguring for the way we use our vehicles. They have to build a vehicle that can operate everywhere from the Arctic Circle to Death Valley, whether the driver is a wannabe race car driver, a soccer mom, or a hypermiler. They have to do it on the smallest possible budget and make it look more attractive to the general public than the competition's vehicle looks. There are plenty of other priorities that they have and we don't, but I don't need to list them all...

many on here and other places have said that a good portion of the grill area is for cosmetic reasons.

even the volt has a non-functional grill. they put it on there because that is what the consumer expects a car to look like.

Especially on trucks. A big grille makes it look "tough" Take my truck for example. I calculated that I have nearly 6 square feet of grille area on the front of my truck. The engine is a Chevy small block 350. The same engine that was put in the Caprice and the Roadmaster. The cars with the same engine had a signifigantly smaller grille. If that engine needed that much cooling then the cars would need a grille just as big.

-Jay

Remember that under normal operating conditions that engine works harder in the truck than it does in the cars They don't upgrade the radiator from a dual and triple core in the trucks from the single cores in the cars for nothing. I've got a decently sized grille and if you stand in front of the D when the engine is nice and toasty when it's revved to even 2k your shirt gets sucked to the front. Lugging up a hill for an hour I'm sure the big grille is appreciated by the engine.

Thanks for the interesting discussion. I think I'll go with my radiator 95% blocked for the winter. That will leave a 1 inch gap at the very top of the core. I saw coroplast mentioned. I'm not familiar with this product. Can some one enlighten me?
Also, just as an FYI. I've heard but have yet to substantiate that my trucks radiatior is the same size as what is used with V8 engines. Is there anyone that can provide further info?

Coroplast is plastic shaped just like common corrugated cardboard (as used on boxes). Coroplast is commonly used for campaign signs, spam signs, and scam signs. Take some road spam off of the road and you're doing the community a favor as well as getting free material, or ask a poltician after an election if you can have his old signs.

Ask:
A dealer parts and/or service manager.
Any Radiator shop.
Most any mechanic with initials on his shirt.
1-800-Radiator (ask the manufacturer)
The Vehicle Manual (the part titled: Capacities)

I've been experimenting with this recently. I have a 96 3.8L camaro. These cars have to front grill. all the air that goes into the radiator is scooped up from underneath the nose. I have a good 60 - 70% blocked with cardboard, and it is doing pretty well. I have to turn on my fans every once in a while in town, but it's due to get colder around here very soon. So i'll probably be able to block even more. Also my fans don't turn on till around 250 degrees, so i do it manually.

Is it normal in that car for them not to come on until 250, or is that a modification?

I thought the stock running temp for a GM vehicle was 195, with the fan coming on around 205.

250 IIRC is past the boiling point of even a 50/50 mix of coolant/water? 205 maybe...


Anyhow, I'd like to run a grille block myself, though I have no a/c parts to put the block between. I thought about maybe running a full grille block over the very front of the grille? It'd probably improve aerodynamics as well.

Yes, a full grille block in front of the grille will improve aerodynamics. A radiator block, up close to the radiator and allowing air to flow past the grille and into the engine compartment but not through the radiator, does not (in some cars it may do a little aero improvement). A popular compromise is a grille block directly behind the grille, still preventing air from entering but much less visible. Look for pictures of Jay's to see one example.

https://www.fuelly.com/attachments/fo...127046ac91.jpg

https://www.fuelly.com/attachments/fo...e03388c138.jpg

I'd have offset the holes to use more of the radiator.

Shatto: By all means, do what is best for you & your situation. What is pictured works for my vehicle in 100F heat in city traffic, without running the engine too hot, and still have the A/C perform reasonably well. Your personal combination of vehicle, climate, and types of driving you do may require something different.

Oh, stop it!

I wasn't attacking you, I was commenting on functionality.
The holes are along the same radiator tubing. Offset holes would provide air to more of the tubes. But it might make no nevermind anyhow.

I didn't take that as an attack. I was merely stating that in my climate and driving conditions what I have works. Your vehicle & climate may be different. The first hole is lined up directly in front of the auxillary oil and transmission coolers. The second was placed to balance out the first, for a symmetrical appearance.

Yeah 205 F fan turn on for my xB and by then the cooling system is up to pressure and the water pump is weeping some coolent. Ideally you don't want to prevent the fans from cooling the radiator at all should them come on so blocking up front where it is easier to remove and not blocking the radiator core was my plan. I just insert white plastic foam sheets into the grill recess - put the upper one in two days ago since the colder weather is here and I wanted a little more heater heat. One down side is I need to monitor the engine coolent temp so I will have to give up a Scangauge number to that.

I was able to block up the lower grill about 65-70% for summer, will probably be about 90% blocked for winter. Upper grill which is smaller, is now 100% blocked year 'round. When the seasons change I keep an eye on the engine coolant temp via ScanGauge to make sure it stays where it normally would be.

With the radiator located a good 8" behind the grill, the fact that some grill is open enables good air flow whenever the electric fan does come on. True that the opening is not huge but it's enough to let the fan do it's job. My a/c condenser is on one side and the rad is on the other. The unblocked grill is in front of the radiator. A/C side of grill is always fully blocked but when the condenser fan comes on it pulls in air via the open area that's over on the other side of the grill so the a/c works nicely.

Check on it as the seasons change. It's important to set it up so that whatever season you're in, the fan isn't coming on all the time. If it is, you need more open grill area.

Learn the temp range it's usually at with no blocking in moderate weather, say 60-70 degrees. Mine hangs out around 179-182 deg. F., 186 with a moderate upgrade climb. If the grill blocking makes it consistently hotter than your 'standard' then you might want to reduce the blocking.

If you have a ScanGauge or other digital readout, you should be able to see engine temp on the screen. Summer weather with engine idling showed me how the fan is programmed. I saw my coolant gets up to 204 or 206, and very rarely it will get up to 208. Temp starts down from 204-208 and will go into the 190's before it starts increasing again. Running down the highway I don't think the rad fan ever came on, unless I still had too much winter blocking in the grill. So I'd remove some, to get it to stay in the low 180's always.