Blocking up the radiator grill

S-Murph

I read on askaboutmoney I think it was, that blocking up <90% of your grill on a diesel with cardboard in this weather will improve fuel efficiency and reduce the time it takes to heat up the engine.

Has anyone done this before? - would it not make one part of the radiator really hot and possibly damage it?

And also, iv been reading my van manual. It says when starting in cold weather not to leave it running to heat up. Rather, to drive it straight away. Wouldnt that cause engine wear?

I always thought its recommended to leave your car/van running for a couple of minuites in the morning to heat up??

thanks.

S-Murph

S-Murph wrote: »

I always thought its recommended to leave your car/van running for a couple of minuites in the morning to heat up??

thanks.

100% incorrect, start and drive leeping revs low till the engine is up to operating temperature.

maidhc

S-Murph wrote: »

I read on askaboutmoney I think it was, that blocking up <90% of your grill on a diesel with cardboard in this weather will improve fuel efficiency and reduce the time it takes to heat up the engine.

That won't make a blind bit of difference other than to make your car overheat easier. The engine has a thermostat which shuts off the water circulating until it reaches a particular temperature in the block (generally about 85 degrees). So the rad is essentially doing nothing anyway until the water reaches operating temperature.

Diesels take generally take much longer to warm up in winter than petrols. It is just a characteristic of the engine.

v300

RoverJames wrote: »

100% incorrect, start and drive leeping revs low till the engine is up to operating temperature.

HARSH ?

Warm up before driving is OK, as is driving away to warm the engine.

The Greens hate us to warm up a car while stationary,
but I like to be able to see out and will defrost the car
with the interior heater, which takes 6 minutes these mornings.

Blanking the grille is irreverent as all cars water cooled cars
have thermostats fitted.
Blanking the rad is an old thing from the 70's.
Do it by all means if it makes you happy,
but remember engines cost a lot of money to replace..

peasant

S-Murph wrote: »

I read on askaboutmoney I think it was, that blocking up <90% of your grill on a diesel with cardboard in this weather will improve fuel efficiency and reduce the time it takes to heat up the engine.

Wrong.

Every watercooled engine has two coolant cycles, a small one and a big one.

In the small one the coolant only circulates from the engine to the water pump and back.

Once the engine is hot, the thermostat opens the big cycle which includes the radiator.

So, on warming up, the coolant never passes through the radiator, blocking it off makes no sense.

What would make sense is to turn off the heating, as that is part of the small cycle ...but in this weather where you need warm air to keep your windscreen from icing up, that could be a tad dangerous.

v300

v300 wrote: »

HARSH ?

Nope, having a car idle at 1000 ish rpm from cold for a few mins is worse for engine wear than driving from cold and gently accelerating to no more than 2000 / 2500 rpm.

v300

peasant wrote: »

What would make sense is to turn off the heating, as that is part of the small cycle ...but in this weather where you need warm air to keep your windscreen from icing up, that could be a tad dangerous.

Some of the TDI's D-4D's are not using the main rad in this weather.

ALL the heat of the engine is going into the cabin to keep
the occupants from freezing.

langdang

peasant wrote: »

What would make sense is to turn off the heating, as that is part of the small cycle ...but

... female passengers will complain a lot...

denat

RoverJames wrote: »

100% incorrect, start and drive leeping revs low till the engine is up to operating temperature.

This is exactly what's recommended in the manual for my 1999 corolla - ie drive on after starting, don't leave engine idling before moving off.

Somewhere in this house, I have a manual for a 1959 VW Beetle (aircooled), my Father's car, and it recommended exactly the same.

That VW manual also had very succinct instructions for parallel parking. They work for me for any car I've driven.

Maybe there are some immutable truths, after all.

v300

denat wrote: »

This is exactly what's recommended in the manual for my 1999 corolla - ie drive on after starting, don't leave engine idling before moving off.

That's a sop to the Greens to help prevent pollution,
as was the 155mph ECU speed limiter for cars on the AutoBahn.

JHMEG

maidhc wrote: »

That won't make a blind bit of difference other than to make your car overheat easier.

peasant wrote:

Wrong.

Forget the rad. In this weather the air is cold enough to chill the engine block. Some engines will suffer more, eg those whose exhaust manifold is to the back, as the freezing air is coming thru the grill straight onto the block itself.

I have seen partially blocking the grille recommended on other forums, and in very cold weather it can produce results.

Voodoomelon

I was actually watching my engine temperature a lot today, when the car gets moving above 50kph, the temperature of the engine drops dramatically, from the needle sitting in the middle where it should be right down to the blue.

After sitting idling at lights for 2-3 minutes, the needle was almost right back up again. Cold temperatures really has an effect on the temperature of the engine once the freezing air starts flowing in.

JHMEG

Voodoomelon wrote: »

I was actually watching my engine temperature a lot today, when the car gets moving above 50kph, the temperature of the engine drops dramatically, from the needle sitting in the middle where it should be right down to the blue.

I have the same. In the middle is 5 bars, but if I have the cabin heater on once I start moving it drops down to 2 bars

Voodoomelon

Yup, actually having the heater on in the cabin is an indirect way of cooling the engine.

Mine was annoying me today, the engine temperature was down in the blue zone as it was freezing outside, and I couldn't get any heat into the cabin. I had both the passenger and driver side set to the max 32°C and there was still only luke warm air coming in after 45 minutes driving.

I think I figured out what was wrong though, I had a large Coke from McDonalds sitting in the front cupholder, and right behind it (an inch away) is the thermometer that monitors the cabin temperature. I think it was cooling down the surrounding air and preventing the proper heated air into the cabin. I'm not sure if this is what caused it as I arrived home soon after.

peasant

In my day, we just wore a hat, scarf and gloves when going for a drive in the winter

ronnie#1

Voodoomelon wrote: »

I was actually watching my engine temperature a lot today, when the car gets moving above 50kph, the temperature of the engine drops dramatically, from the needle sitting in the middle where it should be right down to the blue.

After sitting idling at lights for 2-3 minutes, the needle was almost right back up again. Cold temperatures really has an effect on the temperature of the engine once the freezing air starts flowing in.

I wonder is your thermostat gone???

maidhc

Voodoomelon wrote: »

Yup, actually having the heater on in the cabin is an indirect way of cooling the engine.

Nothing indirect about it. I had the heating on full blast in the Capri in a traffic jam in waterford. It was the only thing keeping the needle out of the red.

As an aside, new cars seem to have a "dumbed down" temp guage. The old temp guages show the car running cooler on a cold night, but in the modern cars the needle goes up the middle and plants itself there come hell or high water.

the merchant

ronnie#1 wrote: »

I wonder is your thermostat gone???

+1

thermostat stuck open.

Voodoomelon

I think there might be air in the loop, i'll give it a good bleeding soon.

maidhc

maidhc wrote: »

As an aside, new cars seem to have a "dumbed down" temp guage. The old temp guages show the car running cooler on a cold night, but in the modern cars the needle goes up the middle and plants itself there come hell or high water.

The temp gauge on new cars is showing exactly what's going on in the engine bay, a constant temperature.

maidhc

RoverJames wrote: »

The temp gauge on new cars is showing exactly what's going on in the engine bay, a constant temperature.

That is impossible, even with modern cooling systems. My understanding (although I have no source for it) is that modern guages are buffered, and so long as the engine temp stays within the boundaries of what the manufacturer deems acceptable the needle stays in the middle. Idiot proof in another word.

The buffering is about 3 degs, the needles dropping in cold weather with good air flow on older cars that folks are claiming to have observed is either fiction or really poor cooling systems. Once an engine is at 90 deg the heat generated by an engine will offset any cooling from airflow. I reckon your Capri was needing attention too if you had to resort to hot air in the cabin to keep it from overheating.

maidhc

RoverJames wrote: »

I reckon your Capri was needing attention too if you had to resort to hot air in the cabin to keep it from overheating.

Tell me something I don't know!

Oddly enough it has behaved itself well since that incident 3 years ago, a rad flush seems to have cured it, although I think an electric fan wouldn't go astray.

I don't see how an engine at 90 deg will offset the cooling from airflow though though. Again, complete opinion on my part, but the radiator is at the front, and a flow of air at -1 will have to be better than a flow of air at +25. If it wasn't there would be little point in fitting intercoolers, and heatsoak wouldn't exist as a word in the dictionary.

Stephen

A lot of truck drivers in the US do this during the winter, but that's on massive Peterbilts and Kenworths, I'm not sure if it'd be much use on a car They usually have the whole grille covered up except for a small diamond-shaped opening in the centre.

maidhc

maidhc wrote: »

Tell me something I don't know!

Oddly enough it has behaved itself well since that incident 3 years ago, a rad flush seems to have cured it, although I think an electric fan wouldn't go astray.

I don't see how an engine at 90 deg will offset the cooling from airflow though though. Again, complete opinion on my part, but the radiator is at the front, and a flow of air at -1 will have to be better than a flow of air at +25. If it wasn't there would be little point in fitting intercoolers, and heatsoak wouldn't exist as a word in the dictionary.

You're forgetting about the thermostat, engine hot, cold air cooling rad, coolant temp drops along with engine, thermostat closes until engine hot again, thermostat opens, engine cools again if the cold air is still there, then thermostat closes again............. thermostat can open and close loads of times over the course of a few mile spin. The stats are rated to an exact temp and will maintain the engine at that constant temperature.

The thermostat failed on my Dad's Hyundai Accent last year, the gauge only get up to a quarter way even on a long spin due to the air cooling the rad and the stat not closing.