DEFENDER2.NET - View topic - TD5 T7 Pre-Heater

↓ Advertise on Defender2 ↓

Home · FAQ · New Posts · My Posts · PMs · Search · Members · Map · Calendar · Profile · Donate · Register · Log In

Home > Maintenance & Modifications > TD5 T7 Pre-Heater - now air in system?

Page 1 of 1

Print this entire topic ·

steve_c3

Member Since: 30 Apr 2015
Location: Hants
Posts: 179

TD5 T7 Pre-Heater - now air in system?

I wondered if anyone can give me some guidance on the coolant system on a TD5 - in particular, bleeding it.

The Kenlowe PreHeater that was already fitted when I bought the vehicle decided to give up last year and a couple of weeks back I finally got around to sorting a replacement and settled on a T7 pre-heater - just in time for the bad weather!

Rather than drain the system (with hindsight, this may have been easier) I simply unclipped the hoses, blocked the flow and refitted them to the correct inlet/outlet of the new heater. I lost maybe half a litre of coolant which I topped up with the bleed screw on the top hose out so that when the coolant flowed out of it, I screwed it back in.

Started the engine, got it to temp, loosened the bleed screw some air came out until coolant flowed so assume it had bled. However, I think there is still air in the system as you can hear it bubbling through the preheater when the engine is off but the Preheater is running. I've read various threads but is there a better way to bleed it?

Cheers in advance

Steve 2002 Defender 110 CSW TD5

28th Feb 2018 2:26pm

geobloke

Member Since: 06 Nov 2012
Location: Nottinghamshire
Posts: 4410

Hi Steve. Sounds like you have done everything right. The TD5 is supposed to be a "self bleeding" system, however I always find that aiding the bleeding by pumping whatever coolant hoses I can reach helps to dislodge errant bubbles.

Other methods include getting the coolant up to temperature, then parking the vehicle nose up on a slope for 15-20mins. This will help with trapped air in the heater matrix.

After that it is a case of doing a number of hot-cold-hot-cold-etc and keeping an eye on the coolant level, topping up as necessary. Keep a bottle of pre-diluted anti-freeze in your cab.

Could I ask for a few pictures of your T7 setup please?

28th Feb 2018 3:29pm

steve_c3

Member Since: 30 Apr 2015
Location: Hants
Posts: 179

Thanks for the reply and good tip on the hill, I'll try and do it over the weekend - also got a premixed bottle ready for top ups.

This is the install below. The first pic shows it in position but with the old Kenlowe heater still in there. The second photo shows it all connected up. Its a neat little unit and all enclosed so no separate pump like the Kenlowe. Initial test looked good and it got the block temp up to about 75 degrees. This was in the workshop so no chill factor to take into account. It's not speedy but it is only the 2kw version - the Kenlowe that came off was a 3Kw. At £75 delivered, it's worth a shot!

The power comes from a socket mounted on the front bumper that I plug a mains cable into.

Once I'm happy theres no air left in the system, I'll do a proper timed test on it and post the results.

Click image to enlarge

Click image to enlarge 2002 Defender 110 CSW TD5

28th Feb 2018 4:25pm

geobloke

Member Since: 06 Nov 2012
Location: Nottinghamshire
Posts: 4410

Super install. Have pondered on these heaters for many years, hotfrogs and alike.

You have mounted that heater very low down so I do not expect there will be any trapped air in it, if anywhere it will be in the heater matrix or quirky little ports in the engine.

28th Feb 2018 4:28pm

steve_c3

Member Since: 30 Apr 2015
Location: Hants
Posts: 179

I've just had another quick look at this at work and found the following...can anyone confirm if this sounds right?

Coolant at correct level for Cold.
Preheater on for 10mins - block gets up to 20 degrees.
Preheater on for 20mins - block still at 20 degrees - previously this has got to 75degrees.
Coolant bottle feels cold.
Top pipe feels warm.
Remove bleed screw - coolant coming out.
Turn off preheater and start the engine, run for 10mins to get a bit more heat in.
Expansion bottle is now 3/4 full.
Engine still running,
Open bleed screw.
Get nothing.
Remove bleed screw - still nothing.
Squeeze top pipe - still nothing. Like theres nothing in it.
Loosen cap on expansion tank - top pipe fills with coolant and starts spurting out - replace screw quickly!

It seems that once the coolant gets to about 20degrees the top pipe empties? 2002 Defender 110 CSW TD5

28th Feb 2018 5:42pm

dorsetsmith

Member Since: 30 Oct 2011
Location: South West
Posts: 4554

Click image to enlarge

B for 1998 to 2002 cooling system A for 2002 to 2006 EU3 cooling system showing flow

your new heater has a pump built in

28th Feb 2018 6:08pm

steve_c3

Member Since: 30 Apr 2015
Location: Hants
Posts: 179

Thanks for the info. I guess the thing I need to know is whether the top hose should be full of coolant at all times even when the engine is stone cold? Could anyone enlighten me by giving their hose a squeeze

Mine seems to empty when its cold and I don't know whether it always has or if it even should? If it shouldn't drain then I need to investigate why. 2002 Defender 110 CSW TD5

2nd Mar 2018 5:17pm

jst

Member Since: 14 Jan 2008
Location: Taunton
Posts: 8329

2011 Defender 110 Puma 2.4 USW Stornoway Grey

the top hose out of the rad? yes that should always be full of coolant. there shouldnt be any air in the coolant system.

is the flow through the preheater the correct way around?

when you say the block gets to 20Deg do you mean the reading on scanguage/temp sender or you user lazer thermometer? Cheers

James
110 2010 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop

2nd Mar 2018 6:13pm

steve_c3

Member Since: 30 Apr 2015
Location: Hants
Posts: 179

James, that’s what I thought. I’ve got a laser thermometer so have been using that to check temps. I’ll check the hoses again in the morning when it’s cold and see if lifting the coolant bottle to help gravity do it’s job does anything and top up if need be. 2002 Defender 110 CSW TD5

2nd Mar 2018 9:52pm

jst

Member Since: 14 Jan 2008
Location: Taunton
Posts: 8329

Does the preheater try to pump coolant the wrong way and the system, thermostat? Stops it going all way around so it signed in air one end ?

If you just run the engine does the top hose empty? Cheers

James
110 2010 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop

3rd Mar 2018 9:06am

Page 1 of 1

All times are GMT + 1 Hour

Jump to

< Previous Topic | Next Topic >

Posting Rules

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum