Coolant Flush and Heater Problems

**sierrafery** · 27th February 2019, 11:03 PM

Originally Posted by Lemo

To help you out with the flush refill, the method to fill is as follows
1 - remove the header tank and place above the engine
2 - remove the bleed screw from the top radiator hose
3 - fill header tank with OAT coolant and water mix until it starts running out bleed screw, tighten bleed screw.
5 - replace header tank, get engine up to temp and check level in header tank and top up as required.

Just an addendum to the above procedure which is the result of many tests made by me(strangely the numbering jumps from 3 to 5 which lets room for nr 4 which is my addition)

so at the end of nr 3 would be "tighten partially the bleed screw"
then 4. start the engine and ask somebody to keep the revs steady above 1500rpm untill no bubbles are coming out near the partially tightened screw then tighten it completely... to explain: at 1500rpm the mechanical bypass valve in the thermostat opens so it will let the coolant from the bottom circuit(which contains the matrix) to flow toward the top hose.

Also if it was flushed with water aprox 5l will not exit the system through the drain hole so as the system's capacity is 13l from dry better fill with 6l of unmixed OAT then top up with water untill it's full(will take around 2l)...then the mix will be close to the recommended 50% cos if you fill the system after a flush with 50% OAT mix the final concentration will be around 30%

And it's important to tighten the tank's cap well to maximum as it's pressure valve to work as it should.

**AK83** · 27th February 2019, 11:45 PM

Originally Posted by sierrafery

...

so at the end of nr 3 would be "tighten partially the bleed screw"
....

YES! .. any more than partially .. and it will almost certainly snap off!

I also doubt that you'd have done irrevocable damage in a short time.
I've incorrectly bled some of my cars, and they don't really get as hot as the tempo gauge says.
On my D1, I have the normal dash gauge and a coolant gauge.
Dash gauge flys into the red, but coolant gauge shows more like high 90's at the same time.
Doesn't mean don't pull up and sort it .. just a comment that the dash gauge is probably taking a reading off the steam/vapour will will be hotter than the actual coolant.

oe. when I first stuffed up the bleeding process, and had the same result 10 mins later down the freeway .. I'm pretty sure that if there was any terminal damage done with the dash temp gauge into the red, I'd not have covered nearly 60K klms since that first stuff up.

OH! ... and blacknights coke bottle tip is the easy way to do it.

**sierrafery** · 28th February 2019, 12:35 AM

Originally Posted by AK83

YES! .. any more than partially .. and it will almost certainly snap off!
.....

No it will not...(though that "partially" involves some common sense as to tighten it untill about 1mm is left as to be enough room for the air to get out) that's how i've been doing it for years and never had a problem and it was proven to me that it's better than the ''official" method from RAVE based on my own experience cos there are many bubbles near the screw with the engine rev'd above 1500rpm untill a clean flow of coolant comes out there ... i'd not compare a D2's cooling system with a D1's though.

**trout1105** · 28th February 2019, 04:01 AM

Dash gauge flys into the red, but coolant gauge shows more like high 90's at the same time.

The D1's must have a FAR superior temp gauge/sender fitted to them than the D2's have because usually the D2 dash gauge will not move from the halfway mark until temps get above about 120C.
When my head gaskets failed on my D2a the temp gauge was still at the halfway mark But my scangauge was reading 124C, Only then did the dash gauge start to move north.
Luckily for me I didn't have to rely solely on the dash gauge otherwise I would have completely destroyed the engine by the time the gauge on the dash showed that I had a problem.
I use the same technique as sierafery does by cracking the bleed screw to get the remaining air out of the system and have yet to destroy the bleed screw by doing this

**AK83** · 28th February 2019, 08:11 AM

Originally Posted by trout1105

The D1's must have a FAR superior temp gauge/sender fitted to them than the D2's have because usually the D2 dash gauge will not move from the halfway mark until temps get above about 120C.
When my head gaskets failed on my D2a the temp gauge was still at the halfway mark But my scangauge was reading 124C, Only then did the dash gauge start to move north.
Luckily for me I didn't have to rely solely on the dash gauge otherwise I would have completely destroyed the engine by the time the gauge on the dash showed that I had a problem.
I use the same technique as sierafery does by cracking the bleed screw to get the remaining air out of the system and have yet to destroy the bleed screw by doing this

Yeah, I hear 'ya.
My D2 got to about 120-ish when the gauge started moving, and then I think into the red once at about in the low 120's using OBDII device.

V8's bleeder is about 4x thicker and stronger than the TD5.
Maybe M8 sized on the V8, maybe M2 sized on the TD5!

On the topic of gauge and temps tho, my comment is to highlight what I've seen.
a non bled system may not show true temps, as it may not be recording actual temperatures.
So gauge may indicate seriously hot with the needle in the hot zone, but it may not necessarily be that hot(ie. into the mid 120's or so)

**sierrafery** · 28th February 2019, 08:52 AM

Originally Posted by AK83

My D2 got to about 120-ish when the gauge started moving, and then I think into the red once at about in the low 120's using OBDII device.

Sorry m8 but it seems that you don't know how that badly engineered system is working... it's normal for the factory fitted gauge to stay at the middle between 70 and 115 then only from 120 it goes to the red zone and all this oddity is based on the factory fitted ECT sensor input while then gauge has preset positions...so if you have additional ECT gauge which shows less or more and you are sure it's reliable the first move should be to replace the vehicle's ECT sensor to rule it out rather than thinking of other more serious things or supposing that somebody doesnt know how to bleed the system without using a cola bottle

.....check this out

temp gauge.jpg

**gromit** · 28th February 2019, 12:32 PM

The sender on most cars has a 'flat spot' mid range so that for a range of temperatures the needle sits in the middle. This is so customers aren't back to the dealer complaining the temperature is a bit high/low all the time.

With my Defender I have always filled, run till warm then bled at the two points & topped up. Coolant changed every 3/4 years for about 18 years with no problems. I've read the coke bottle method and wonder why it's needed.

Colin

**Blknight.aus** · 28th February 2019, 08:02 PM

Originally Posted by gromit

The sender on most cars has a 'flat spot' mid range so that for a range of temperatures the needle sits in the middle. This is so customers aren't back to the dealer complaining the temperature is a bit high/low all the time.

With my Defender I have always filled, run till warm then bled at the two points & topped up. Coolant changed every 3/4 years for about 18 years with no problems. I've read the coke bottle method and wonder why it's needed.

Colin

its quick, easy and means you dont need to move things around. It also lets you see whats coming in and out of the expansion tank, nasty floaties (chemiweld) oils and rusty bits wind up in the bottle...

it also means I can leave the engine idling and go check some other things with an easy to spot tell tale as to how the things doing while doing the service work.

**Lemo** · 28th February 2019, 08:29 PM

So next time I do a coolant flush/change and use the coke bottle method, do I still bleed from the top hose?

**sierrafery** · 28th February 2019, 08:37 PM

Originally Posted by Blknight.aus

its quick, easy and means you dont need to move things around.

I respect your tutorial and i think that your trick it's a brilliant one for 300Tdi or others but quoting from your post:

Originally Posted by Blknight.aus

when that stops bubbling air in keep the revs on and check by hand the temperatures at the thermostat housing (dont do that on the TD5, you will loose an arm to the belt use the port on the top of the engine on the passangers side where youd expect the thermostat to be)

, i'm a bit confused or i misunderstood what you meant as AFAIK you can't expect a thermostat to be on the top of a Td5 engine, the Td5's thermostat works in a different way than the 300tdi's... so a priori with my apologies i insist that the method described by me is the best for a Td5

also

Originally Posted by Blknight.aus

....have the heater on flat out so you can check that its flowing correctly as well.

that's completely useless for the Td5 as the heater matrix is under full flow all the time, the heating is managed by the heater assembly's flap systems which are not affecting the flow whatsoever regardless of the setting ... no offence, i just want to share my own 12 year experience ONLY with Td5

Thread: Coolant Flush and Heater Problems

Thread Tools

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions