Grill Blocking for a 4.3L Engine
 

In the fall/winter/spring, I use a piece of cardboard (34"x16") to partially block my radiator core (34"x19") in oder to bring it up to operating temps quicker. The results have been good. I've been thinking about trying it during the summer months and would like opinions and experiences. Has anyone tried this on a similar engine? If so, what what was the size and type of material used? Do you recommend blocking the bottom or the top of the radiator?
Thanks in advance for your expertise and assistance!

What make/model vehicle are we talking about?

I have used a partial radiator block on my Insight for thousands of miles, even in higher temperatures, so far up to 85 degrees.

I have found it gives me about 10% better mileage. The block is a simple plastic "For Sale" sign that I can fold up to reduce the amount of coverage. If my car runs hot enough the radiator fan (electric) will just come on more. This provides me with insurance against overheating. I have never seen any difference in coolant temperature according to the guage. It definitely helps with winter warm ups.

I believe the reason it works is because it allows the coolant that is returning to the engine to be warmer than it would be if the air temps are low enough.
My experience in working on cars for 30 years for a living, was that coolant temperatures going into the engine will vary greatly depending on several conditions.

How clean is your radiator? If the radiator is cooling as new, then when temperatures are cooler the outlet coolant temperature can vary by as much as 70 degrees. When ambient temperatures are freezing and especially at even lower temperatures that some here experience, that can cause the engine to loose significant heat to the much colder inlet coolant temperatures.

regards
gary

I've run 100% radiator blocking on my 2002 GMC 5.3L V8 and my 2008 VW 2.5L I5. I haven't had a chance to run either of them far into the summer. I have run the VW on isolated warm days (80 degrees) and I've run the GMC in at least 70 degrees. Neither have overheated.

goldie

I would say to you, watch the temps. I assume you have a coolant temp meter in the cab. make sure you put the block on in such a way that it is easily removable on the fly. I would use zip-ties (wire ties, the plastic kind) and carry some dikes (diagonal cutter) in the car with you. if the thing starts overheating or getting uncomfortable, just cut it off.

if you find that it works for you and that you like it, make it more permanent and pretty it up a bit.

it's all about experimentation. I would search the users here and see if anyone else has this type of vehicle. not that the engine size doesn't matter but I would think that the body type would be more important.

I've done it before successfully as well.

If you have a temperature gauge (and not just an idiot light) that will help you watch for dangerous situations.

It might be an issue if you get stuck in a traffic jam or something.

-Bob C.

In my 98 GMC K1500 with a 5.7 V-8 I have two 4 inch holes cut into my grille block... In 100+ degree heat the coolant was getting a little warm, but the main reason I did it was because the a/c performance was diminished with only one 4 inch hole.

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

Thanks to all for the information. Now I have some good ideas to experiment with on my vehicle. Just for the record, my vehicle is an 07 Sierra P/U with a 5 speed manual trans. The vehicle has 17,100+ miles and I have on board gauges. Here in NW Indiana, summer temps reach into the mid to high 80's on a regular basis with stretches of 90+ degrees. I guess two options I can try are to partially cover the front of the A/C core, the A/C core has about 3" between it and the radiator core. (I usually don't use the A/C unless I'm desperate!) Or, what I'm leaning towards, trying is to cover the bottom 1/3 of the radiatior core with a quick removal system. And then go from there. Again , thank you!

The best way to experiment with grille blocking is to use duct tape. Its easily removed if you accidentally block too much, and is low cost, and easy and quick to do. If you find the duct tape works, then fabricate something prettier.

-Jay

For a Sierra you may be interested in looking at the detailed thread where I put a stealth grille block in my 98 GMC Sierra...

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