T25 early cooling system too efficient

[Wilber]

So my dilemma is not overheating, a common enough fault with any vehicle, but underheating.

As my daily I run a panel van with a slightly modified 2.1 DJ engine which has an early cooling system which as stated seems to work too well. Instead of the fuel injection system I run twin Dellortos and am very happy with the results, puts a smile on my face and surprises a lot of drivers off the lights.

The temp gauge barely moves even on a long drive so have replaced the thermostat with a new tested one, changed the temp sender unit, filled it with the correct mix of anti-freeze and re-bled the entire system.

No change

Now the only thing I can think is that thermostat is opening too soon and not giving the engine a chance to get to full working temperature. BTW the thermostat and expansion cap are from GSF. This could be the reason but I don't know any difference between these products and the ones sold by Brickwerks.

So after a lot of research online I have currently installed a very cheap alternative, cardboard to partially cover the radiator. The results are outstanding! I have covered approximately 80% of the rad and the van warms now and runs far better with the needle bang on in the middle of the temp gauge.

The main concern with this system is remembering to remove the obstruction as the ambient temperature rises. May need to conduct some tests.

So my questions are:

-          Has anyone else experienced underheating with their cooling system, with a known working thermostat?
-          Does anyone else use the card board trick to aid heating in the winter?
-          If the card board aids in cooling does that mean the thermostat is opening too soon?

[Ian Hulley]

BTW the thermostat and expansion cap are from GSF. This could be the reason but I don't know any difference between these products and the ones sold by Brickwerks.

Buy the real parts from Brickwerks ... GSF sell cheap parts, Brickwerks FIT the parts they sell. That's the difference.

Ian

[Wilber]

Hi Ian,

That's what I thought regarding quality but not too sure if it will change the under heating / over cooling issue.
What I would need to know were the specified:

The pressure opening for the GSF and Brickwerks caps.
The opening temperatures for the GSF and Brickwerks thermostats.

I could then deduce if either are causing an issue. The quality of the Brickwerks parts are obviously going to be better but does the affect the calculated action of the product?

[ghost123uk]

There is only one thing that can cause over cooling.

An issue with the stat.

Full stop.

It is either faulty, wrong one or not fitted correctly.

Oh, unless someone has re-plumbed the engine so the stat is no longer in the circuit = VERY unlikely

[petethefeet]

Hi all,
It is quite a common failure mode of thermostats to fail by 'opening early' as the coolant gets in between the rubber 'boot' and the stem (pin) that opens the valve. A thermosat will normally last 3-5 years before it needs replacing.
Hopefully you will get more MPG as it warns up quicker when it has been changed.

[Ian Hulley]

Ok, early cooling system flows the other way doesn't it .... We're not looking at the stat waiting for the rad to get to temperature before it opens and getting byepassed are we ?

I know when me and Steve Mocki did Mattpoos we had attack his plumbing to fit a late 2.1 system onto an early 1.9 pipework.

[Oldiebut goodie]

This may help you petrolheads for orientation of thermostat!

[Wilber]

Parts ordered from Brickwerks:

Thermostat - T3 WBX (1.9l & 2.1l)
Header tank cap - T3 (Genuine)

Once fitted I'll update with the results......

[California Dreamin]

Could be the dash pod voltage stabiliser.....hows your fuel gauge reading?

Martin

[Oldiebut goodie]

But the cardboard over the radiator wouldn't affect the voltage regulator causing it to read normal.

[ghost123uk]

That cardboard over the radiator thing always makes me smile (wryly)

[Ian and Lins]

From personal experience; be very careful undoing bolts on/around thermostat housing. Use plenty of Plusgas and only undo those you need to. I cackhanded some and snapped the heads off.

[California Dreamin]

But the cardboard over the radiator wouldn't affect the voltage regulator causing it to read normal.

Indeed...could actually be overheating

Martin

[waltraud]

Interesting dilemma, my early cooling system with 32mm underfloor coolant pipes and early waterpump on a DG was always running far too cool. Heater never got properly warmed up except in hot summer temps. Recently I changed to a new water pump and stat from Brickies. All was well. The engine now gets up to and stays at temp much quicker. The neee used to sit at 1/3 most of the time, now it's always just beyond the middle / red light......I always wonder why it does not sit in the mide but have a theory that- a) some early vans were designed so that the needle sat just to one side of the gauge so as not to obscure the light OR the new, efficient system has shown up other faults like a slight old, perhaps slightly clogged up rad?

Your problem must be stat related- your problem is the exact reason why I got the parts from Brickies- it's a fair bit of careful work on an early system to do things twice.

ImageUploadedByTapatalk1359220521.802037.jpg

[kevtherev]

the clogged rad could well be the reason... after investigation it has been determined mine is a bit gunked up after twenty five years