drilling out thermostat

LIFTED · Post by **LIFTED** » Fri Oct 14, 2011 9:36 pm

Just some Subi chat, A guy came over (mechanic) to buy the rear bumper of my outback I'm parting out and I was having a look at his car(finally!! the first person to actually come over in a Subaru for parts....everyone else has rocked up in another brand of car!!!!)
Anyway he has drilled out his thermostat and permanently wired in the thermo fans so they run all the time the engine is on, as he is worried if his car ever over heats it may damage the engine.
Do Subies overheat easily? an wouldn't drilling out the thermostat make the engine run colder and wouldn't this confuse the ECU ?
Are there any real benefits if doing this?
I did read here that someone has replaced his thermostat with a cooler one, not sure why though?

2nd Hand Yank · Post by **2nd Hand Yank** » Fri Oct 14, 2011 9:58 pm

I would suspect that damaging the t-stat is not helpful, just paranoia.
Sometimes guys with modified engines will pick a t-stat of a lower temperature than factory (160 F instead of 190 F?) to lessen the chances of detonation.

Having a non-functioning t-stat will keep an engine cold and slightly-underpowered under most driving conditions.
My thermometer never rose much off "Cold" if I drove over 50km/h
until I replaced the thermostat.

Colder engines probably pollute more as complete combustion is harder to achieve.

pitrack_1 · Post by **pitrack_1** » Sat Oct 15, 2011 12:01 am

And without a thermostat and therefore running cold, your engine may stay in 'choke' mode perpetually trying to warm up. This may dilute your oil and raise your fuel consumption.

I have two cars- a N13 Pulsar and a Mazda 3- both of which, once the faulty thermostats were replaced, gave better fuel economy (10+%), ran better and the heaters worked in winter too. Mind you, I'm from Canberra and it was -2C a couple of nights ago still!

Wiring fans fully on may only exacerbate this cool running and place extra load on the alternator. If this is required, I'd suggest the vehicle has an overheating problem caused by something else.

steptoe · Post by **steptoe** » Sat Oct 15, 2011 3:13 am

I thought the factory holes in thermostat were for air bubbles to escape from a closed thermostat.
Currently running without one and runs about 5 to 8 C cooler - 61C at times.
Thermos on all the time is over the top but I dunno how warm Duncraig is either
Best combustion for economy is supposed to occur in an engine running at about 95C - I read on radiator web site

Tweety · Post by **Tweety** » Sat Oct 15, 2011 6:36 am

I know my conversion is very unconventional but...

When I test rode my ea81 trike recently (it has a 88 degree thermostat and digital temp gauge radiator side of thermostat) it very quickly rose to 100 degrees and I shut it down. I was suss about an air pocket and was correct. The side of the number one cylinder was quite hot.

Once home I consulted a friend, a mechanic that has been racing lotus cars for 30 years. He said that although the thermostat has a very small hole in it he recommended drilling a second hole but no larger than one eigth of an inch to allow for a little more circulation when cold to avoid the air pocket.

I noticed from cold it takes about a minute longer for the engine to get to normal operating temperature.

As for the thermatic fans "on" all the time - with digital switches that are so easy to adjust nowadays I cant see any positive in leaving them running all the time. Its just unnecessary and in the end cause others problems eg takes battery power when starting, longer to warm up etc.

If that helps.

FujiFan · Post by **FujiFan** » Sat Oct 15, 2011 7:22 am

Australia is known to be the hotest and driest continent, but: This dude is not addressing the underlying issues with his subaru by drilling out the thermostat and running electric cooling fans constantly - unless he lives on the mouth of a volcanoe (But maybe he has good

reason)
As with what other contributors here have suggested, extra load on battery, engine never reaching proper operating temp and so on.

Personally I removed the thermostat from an L wagon (carb) yonks ago thinking this would be helpful. But after 50kms+ driving to and from work the engine would NEVER reach specified operating temp, power was slightly down and economy worse off.
The 30k's or so included a drop and rise in altitude of 700m approx (up and down the Blue Mountains, Lawson to Penrith).
A quality new Subaru thermostat will perform as designed to.

J

BaronVonChickenPants · Post by **BaronVonChickenPants** » Sat Oct 15, 2011 10:03 am

Sounds to me like he has taken a known issue and skipped passed all the facts to an ineffective solution.

Issue:
The EJ25's are notorious for needing a rebuild after "overheating".

The details he has skipped over:
By "overheating" we are talking about running out of water, blowing a hose, etc.

No matter of fan or thermostat modification is going to save you in this situation.

Jordan.

LIFTED · Post by **LIFTED** » Sat Oct 15, 2011 11:12 am

Yeah I thought it was strange but he said he was a mechanic and must have some car knowledge. I was thinking Subaru would have spent a lot in R&D and know what they are doing.

Tweety · Post by **Tweety** » Sat Oct 15, 2011 3:29 pm

I agree. We have all believed at one time or another that we know more than the manufacturer. In some cases this can also be true. Some vehicles just came out with faults. We are not talking custom vehicles here.

However all water cooled cars came out with thermostats. This enables the engine to warm up as quick as possible to operating temperature at a time when wear is at its peak- when cold. This part also restricts the speed at which water circulates the cooling system, giving it a certain pace at which it passes through the radiator therefore allowing it to cool at its optimum. It also stops the engine from cooling too much. That's the theory I think.

But in some vehicles (for example)a bigger radiator is a good move. The thermostat will still maintain the moderately high operating temperature no matter how cool the bigger radiator is. So there is one modification that is an improvement over the manufacturer many of which try to cut costs with a minimum size radiator.

You can spend hundreds of dollars on bandaid solutions to problems. I took my old Zephyr to a good mechanic and began to verbal a list of possible reasons why it was over heating. He stopped me in my tracks "nothing beats a proper diagnosis". Turned out the problem wasnt the possibles I suggested but a hairline crack in one of the bores. He was right and I never forgot that.

I believe a thermostat is essential to keeping a vehicle efficient as it was designed.

d_generate · Post by **d_generate** » Sat Oct 15, 2011 3:55 pm

I remember people removing the thermostat on old Holdens & Falcons years ago thinking they would run cooler (N/W Aus where it's hot one day & hotter the next) it was ok in the Holden from memory but Fords had a much more efficient water pump and it pushed the water through too fast for it to cool down in the radiator, I worked at a servo in Northampton & we'd have 3 or 4 cars coming through each week with overheating problems usually caused by this mod.

Gannon · Post by **Gannon** » Sat Oct 15, 2011 4:43 pm

Hey Jordan is back!

steptoe · Post by **steptoe** » Sat Oct 15, 2011 6:53 pm

I must have learnt my theory of no thermostat with a Ford bias. I am not gonna stick around on a stinkin' hot day to test this idea of no thermostat being best way to keep its cool _ i appreciate the need to regulate the water flow by temperature

gosurfun · Post by **gosurfun** » Sat Oct 15, 2011 7:47 pm

Old holdens just had a light for the temp if they overheated, if the coolant and thermostat are not too old and your still worried, maybe put a temp warning light on it as well. It gets your attention quicker than remembering to look at the guage all the time and much cheaper than a new whatever gets overheated/cooked needs replacing + towed home. I havn't got a warning light on mine as the coolant and thermostat are not old, its just an idea. I've done the drilling a extra 1/8 hole in it for peace of mind a few times and not had any problems.

mud_king91 · Post by **mud_king91** » Sat Oct 15, 2011 8:19 pm

all in all dont do it

coupe · Post by **coupe** » Sun Oct 16, 2011 8:22 pm

When i used to run Mini Coopers. We used to drill the thermos or we would use a blanking plate. there was a spot in the cooper head that would run hot due to the flow of the water before the thermo would cut in. I have tried all sorts of combinations but i have found just a lower temp thermo works good with a well maintained radiator. You can wire a secondary switch on the thermo fans as a safety measure on hard runs.
Cheers Pete

tony · Post by **tony** » Sun Oct 16, 2011 10:05 pm

the hole in the thermostat is there in case the thermostat jams shut and closes the water circulation off. the hole allows some circulation. never fit a thermostat without a hole, some are sold without one. drill a hole if it does not have one. running without a thermostat makes the motor run cold causes engine wear and uses more fuel.
generally if a thermostat jams it jams open that is the way it is designed, so it does not damage the engine through overheating.

LIFTED · Post by **LIFTED** » Sun Oct 16, 2011 11:19 pm

I've just google'd images of Subaru thermostats and they don't appear to come with a hole in them.

Gannon · Post by **Gannon** » Mon Oct 17, 2011 5:19 am

They have a hole, but it usually has what is called a jiggle pin in it, to allow air through quickly, but only allow a small amount of water through

steptoe · Post by **steptoe** » Mon Oct 17, 2011 7:28 am

I have found more jammed closed thermostats than jammed open, one was in a VZ Commodore. Mmechanic replaced the radiator and water pump first in an effort to fix instant overheating - bad call

mud_king91 · Post by **mud_king91** » Mon Oct 17, 2011 7:45 am

bad mechanic... first thing checked should always be the thermostat its the weak point in the cooling system

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