Another grill cover bites the dust
 

I was in my 1986 Jetta diesel fully loaded as usual today. Cruising at about 55 mph. the outside temp was 100 F with a slight tailwind. I notice that the temp gauge is getting hotter than usual. Nearing the 3/4 mark.

My grill cover was held on with two drywall screws and some cable ties. I pulled over and removed all of it. Within a mile the gauge was back down to 1/4-1/3rd the way up the gauge.

If the trade of more aero vs a significantly hotter engine is the trade then I am going to use a small amount of fuel more.

Usually August is hotter than July around here. It may go back on in the mid fall but not sooner.

Have you considered optimizing the grille block opening ?

size the opening in the worst conditions for it (basically now) and you wont have to worry about it. then you could tape it or have an easy to remove cover for the opening in the winter

The optimum size is the stock opening for this weather and load. I am sure that the engineers at VW considered how much air is required at such load conditions.

actually it could be a little smaller opening since most manufacturers over design for the masses...
but you thought process is very correct Varn.

Let me throw this uot.
I travelled a great deal on a ranch road in my Infiniti Q45. The dust built up in the radiator. Even though I was my car religously, the fine dustg built up and caused overheating....even with two extra electric fans.
When I replaced the radiator......about 20 oz of dirt fell uot..........just sharing my experience.

Yep I agree with your thought.
My car is 250,000 miles young. Is nearly 30 years old. I am one of the masses.

I travel regularly on dust covered roads. This year has really been a challenge. Our road is nothing but dust from the drought and heat. In four miles I can't see anything behind me.Probably my radiator is filled with dust. At least they put in a gauge instead of an idiot light showing that your engine is overheated.

I think I will get my power washer out and see if I can wash any dust out of the radiator.

The dust built up between the A/C radiator and the water radiator. There was a foam ring around the the two radiators that also prevented the dust from washing out.
Now when I spray clean the engine compartment, I stick the spray wand down between the two.

Just FYI - careful about cleaning a radiator using high pressure - you can bend the cooling fins & make things worse. (Ask me how I know.)

Good point. I have one that is gas powered and pushes water much harder than what I have seen at car washes. For now I have good enough cooling and too many projects to worry.

Good Call

Don't forget that you can get buildup on the inside of the radiator as well. You can get rid of some of that by doing a coolant flush and refill.

It's also not fair to assume that the grille opening has to be as large as VW designed it to be. VW designed it to withstand the absolute worse-case scenario: loaded to the max weight rating, in high ambient temperatures, with low vehicle speeds, etc.

Most hypermiling & ecomodding techiques will decrese the cooling requirements because the engine won't be burning as much fuel. I've noticed that P&G, especially EOC P&G affects the time it takes my engine to warm up (an indication of the required cooling requirements after it's warmed up). I estimate that, for me, it takes almost twice as long to warm up with EOC P&G vs normal driving. The reason for this is twofold. First, I'm burning less fuel more efficiently, so there's less heat that needs to be taken away. Secondly, the engine cools down during the EOC portion. After a particularly long glide, I'll notice that my coolant temp gauge moves off it's normal operating temp.

Yep I was at 53 mph with the car loaded to the gills in 100 degree heat with a tail wind. My grill cover was letting less than half the normal amount of air in. It was increasing temp gradually and was nearing the top of the range in the standard gauge.

My car is old and I don't need to replace any components because of over heating.

I suppose I could have removed half of the cover but it was 100 degrees and I was near overheated personally. Removal of the cover settled things down great.

After reading what aerohead says about Hucho and these early vw's, I am pretty convinced that the stock opening is just about perfect for the conditions I described.