Relieving Engine Bay temps - ventilation

[FNQGU]

Gecko - I do like the look of those vents, and was thinking of that exact same spot after looking at the bonnet closely.

As a bit of an update - I put one of those turbo blankets on, and took off for a good long run up to Ravenshoe and Herberton, then off-road to some steep climbs and nearly fried the engine I reckon. Something is wrong as temps are rising and rising when under load. On the highway climbing up through the range into Herberton, it quickly got to 105 celcius before I pulled over and let it cool. Off-road in low-range temps got to 110 celcius at the top thermostat bolt. They would slowly drop back to normal (85 celcius) when I pulled up, lifted the bonnet and let it idle. Freaked me out actually and put an end to testing. We camped up for the night and I babied it home this morning with temps only getting into the mid 90's before I'd pull up and let it cool down. Temps also stayed lower with the aircon offf.

Now got to find the problem.

Radiator fluids are good and there are bugger all bugs or grass seeds in it.

The viscous coupling on the radiator fan could be an issue. I can easily turn the fan by hand.

About to pull the thermostat and make sure it is working properly.

Ceramic coating the dump pipe and turbo could well be an option but I've had this truck purring like a kitten for the best part of the last 2 years and never had any hint of overheating issues, so I am convinced something has recently gone wrong.

The only thing recently changed was the tranny cooler position, however there should still be sufficient air getting to the radiator. I haven't removed this as part of the problem yet though. Tranny fluid temps were beaut the whole time.

Any suggestions will be gratefully welcomed.

[the evil twin]

Uuuuummmm... 110 at the thermostat bolt doesn't necessarily equate to an issue or directly to coolant temps, engine operating temp etc.
Coolant can only take heat away from something that is hotter so it is a matter of determining if the coolant is heating the thermostat housing or is it heat soak.

What was the factory gauge showing at the time?

I do agree the viscous clutch is knackered by the sound of it.

[FNQGU]

Factory gauge went to 4/5ths and was rising when I pulled up. I agree with you but I have never seen it anywhere near that sort of gauge reading before. 110c seems on the high side to me and I'm not comfortable with it.

I couldn't find any leakage on the viscous coupling, but I can spin it with one finger. I couldn't do that before so will pull it out on Monday and see what happens after that.

Re general engine bay temp - the whole area seems hotter than normal at the moment. The intercooler was almost too hot to touch, so can't be of much value in reducing charge air temps, probably making air temps hotter if anything.

[threedogs]

@ FNQGU so you reckon those turbo beanies[thermal cover] are no good ??

[FNQGU]

Sorry for the delay - been out for a bit.

Well, my viscous coupling was Roo-Ted by the looks of it and would appear to have been causing my engine bay temp issues recently. As I understand them, when they are cold they spin freely, and when they heat up they get harder and harder to turn and even lock up to run 1:1 with the engine? Well, mine must have had a leak at some stage, and there was none of that viscous fluid left in it to kick in and spin the fan when hot. I could turn it with one finger. Have ordered a replacement and am hoping this makes a difference but it has got me looking into engine bay temp management and what is normal and acceptable and what is not. I was also recommended to forget the viscous coupling and simply bolt up direct so the fan always runs in a 1:1 ratio to the engine (?). I am still pondering this, as yes it might be more efficient in dragging air through the radiator, but what happens when crossing deep water for instance?

TD - my turbo cover made SFA discernible difference under the circumstances, but I suspect that my overheating issue outweighed the benefits and I hadn't set up any testing gear to try and measure it either. I might play with that a bit in the future, but anything that diverts heat back down the dump pipe has to be a good thing, and it certainly seems to work as I can touch the outside of the cover without burning my fingers.

From a previous post by Old Mav, who would know, it seems that very little can effectively be done as air-cooling an engine bay is not really an efficient way to go unless traveling at speed. That said, there does appear to be a lot of info in the race car scene indicating that bonnet venting can have measurable benefits in managing engine bay heat, and this could apply to 4wdriving speeds. Ceramic coatings and turbo blankets are a very effective starting measure it appears.

The analogy of comparing an open umbrella, or a cardboard box with one end open, to driving an engine bay through the air seems to be used a bit. It is all about high pressures and low pressures, and allowing air to flow freely out of an engine bay without detrimentally affecting flow through the radiator as a result.

The below articles also shed some further light, and I do like the articles from Autospeed:
http://www.speedcafe.com/2012/03/23/...8-supertourers
http://www.autospeed.com/cms/article.html?&A=2159
http://www.autospeed.com/cms/article.html?&A=2160
http://www.autospeed.com/cms/article.html?&A=2162
http://www.autospeed.com/cms/A_2455/article.html
http://www.autospeed.com/cms/A_2456/article.html
http://www.torquecars.com/tuning/exhaust-wraps.php
http://www.hoodlouvers.com/racinghigh-performance/

One thing I noticed during my heat issue, is that my Intercooler is getting seriously affected by engine heat-soak to the point where I doubt very much it is actually cooling any of the charge air, rather is probably doing the opposite if anything. With this in mind, I spoke to ARE about their more aggressive bonnet scoops, and the feeling was that the increased air-flow through the scoop would help in combating the heat-soak issue, however that is not really the intent, as the air should be dragging heat out of the intercooler core down into the engine bay, and perhaps even slightly adding to the heat management issue. At low speeds, a fan beneath the intercooler would have definite benefits. At higher speeds they didn't think so, in fact they thought the fans then became a hindrance.

Lots of food for thought in this area of heat dissipation and aero-dynamics...

[threedogs]

Why not fit a 9" fan under a second scoop to remove heat when travelling slow.
It could be set to come on at a certain temp, as stated usless if travelling
heat rises so GKO's vents seem to look like they would suck heat out at speed.
would a wider scoop help?
http://www.ebay.com.au/itm/Toyota-La...item1c4bf16bb1

http://www.ebay.com.au/itm/XB-BONNET...item3aa1673053
These would lookawesome either side of your scoop on a custom bonnet

Just remembered on my 75s Troopy and some early Range Rovers they had vents on the side of the guards , they were
mainly to keep the battery cool, maybe it would work on a GU as well

http://www.ebay.com.au/itm/BONNET-VE...15776421&rt=nc

http://www.ebay.com.au/itm/BONNET-VE...15776421&rt=nc

[FNQGU]

Thanks for the links. You are the eBay king!

Yesterday I fitted up an alloy spacer block and bolted up the radiator fan direct (whilst arguing about the viscous coupling and warranty...) Anyway, massive difference!

On the Kuranda range where a few days ago I hit 103 degrees, I am now only hitting 91 degrees, when really flogging it, and 88 degrees when taking it easy. Temps also drop rapidly as soon as I ease off the gas, and just off the back of the range I found I was sitting on 77 degrees at the Kuranda lights. Tranny temps were also sitting on a nice cool 75 degrees after having climbed to 80 on the way up the range. On a second run up a 10klm long winding road which is a steady climb, in the middle of the day's heat, I managed to top out at 100 degrees celcius, again, dropping off rapidly to idle at 92 degrees (aircon on full blast the whole way too) when I pulled over at the top. Engine temp was down to 71 degrees by the time I cruised back down to the bottom in 2nd gear.

So, I think in my mind I have identified the viscous coupling on the fan as a major element to watch when it comes to managing engine temps, and thus engine bay temps. Yes, most of you probably just said "duh", but it is all part of the learning curve for me. The fan was still spinning and looked like it was doing its job, but obviously wasn't pulling air like it should have been, plus I reckon that the Engine Watchdog was what brought this to my attention in the first place. Look for any signs of viscous fluid leakage and give it a bit of a turn by hand on a regular basis to check resistance. When I pulled my fan out, it was actually covered in a thin film of the stuff that cleaned up pretty easily.

As an addition to this thread topic - I also had a conversation this morning with the Hood Louvre mob in the USA (link above) who have a lot of experience fitting vents to the bonnets of both race cars and particularly Jeep Wranglers and claimed to have had a NASA engineer involved in design and testing. They are adamant that the louvres work wonders on the Jeep's when the engines are working hard at low speeds (when the radiator fan is doing all the work) and high and low pressures are not really part of the equation. I sent them over a couple of photos of the GU Patrol bonnet with Intercooler scoop and they are going to get back to me with some further recommendations. Will update when they do.

[nissannewby]

Can you look at a clutch style engine fan? Either an air or electric style one. You will use more fuel with the fan running constantly not to mention to noise that comes with the fan running constantly.

At what speed was your testing done at? A fan running constant can also cause restriction at higher road speeds in some instances.

[threedogs]

I used a 5 blade fixed steel fan on my chev troopy but I think that dragged 20 hp out of the motor.sounded like a chopper overhead LOL
I then went to a 6 blade uni plastic fan similar to an OE viscous, much quieter than the steel fan
Would easily hold a sheet of paper to the grill for testing purposes, Plus the fan had to be a certain distance from the radiator
and so far into into the shroud for 100% efficiency.

[FNQGU]

Yeah, I probably wasn't too clear before - I fitted up the direct bolt on fan while waiting for a replacement viscous hub that I believe should be supplied under warranty. Just arguing that out now. The extra noise is noticeable, you're right there! Any suggestions on different types of fan would be appreciated. I was concerned that the electric thermo fans simply couldn't pull enough through the radiator to compare. It would be convenient to have a switch to flick them off for deep water crossings though!

Testing wasn't exactly scientific, but I've been repeatedly running up the same hills at roughly the same times of day when it is at its hottest. Yes, there are no doubt a lot of margins for error in that method, but it is a real-world indicator anyway.