Have removed head to replace blown gasket. Head pressure tested and skimmed, now ready to re-install. Didn't see it when removing the head, but just under the inlet manifold is what appears to be a brass temperature sensor screwed into the head. Of course I have broken the wiring connection and janked out the internals of the device. Oh dear me, said i under my breath !! Don't remember anything being mentioned in the engine manual about this !! It's shown in the diagrams, but no description.
Can anyone enlighten me as to what it is, what it does and more importantly - where's the best place to get a new one. Or is it needed at all ??

- (#13721) gordon davies, 12 Oct 04 14:19

Temp gauge sender. Go to your local factors, it's damn near universal across the Toyota range.

You can x-reference from Toyota number 83420-20020 if you need to...

- (#13721) David Miller, 12 Oct 04 14:24

Dave
Indebted yet again. Many ta's.for super speedy reply

- (#13721) gordon davies, 12 Oct 04 14:38

To add to David's good advice, a lot of us have fitted a better temperature gauge. I have a "Durite" and I fitted this, together with a new head sensor and, for the last three years have had a much improved indication of coolant temperature. The Dave Mason temp alarm gives even better safeguards. It is well known that the standard Toyota gauge is somewhat "all or nothing", ie, the needle in the middle and, in the blink of an eye, into the red, followed by the "bananna head" syndrome.

- (#13721) John Davis (Leics), 12 Oct 04 15:44

John
I know the feeling all too well. Any idea where I can get either the Durite or Dave Mason and roughly how much?

- (#13721) gordon davies, 12 Oct 04 16:34

Gordon

search the web for the former or buy direct from AceAnswers for the latter

- (#13721) Ian Dunse (Derbs), 13 Oct 04 01:18

Hmmm the advert for the Mason Alarm isn't so easy to find now that Dave has revamped the site. Try this link http://www.aglservices.co.uk/Ace_Answers3293.htm

- (#13721) Ian Dunse (Derbs), 13 Oct 04 01:40

Click on Ace Answers at the top of this page, then look for Temperature Alarm, for the Dave Mason alarm.
Durite and others a good spares outlet.
Price wise don't know, however, the Mason Alarm is dead easy to fit, no need to install a replacement/extra temp sender to the engine, (an additional cost to the guage), and it give a better reading guage with the extra feature of an alarm. Have a read.

- (#13721) Clive (Bristol), 13 Oct 04 01:45

Gordon. There are many satisfied users for the Dave Mason alarm so, it must be good. I had fitted the Durite about three years ago and before Dave's device was developed but, anything must be better than the standard gauge. You can look at the Durite, and the ancilliaries, at Vehicle Wiring Products website

- (#13721) John Davis (Leics), 13 Oct 04 02:29

Sorry, have been wary of promoting this device too much. Yes, it's rather hidden in Ace Answers
- Cooling & Heating
-- Temperature Gauge
--- * Temperature Gauge mod & alarm.
And comments elsewhere in that folder.

The main two versions of my device are modifications to the Toyota system (old or new "shape") so you, Gordon, would have to have a working Toyota sensor in the head.

... or ... if you choose to fit a Durite, Tim etc gauge with its own sensor and proper deg C linear scale, then you can fit my "audible alarm only" version to that to alert you to abnormal temperature rise.

- (#13721) Dave Mason (Sussex), 13 Oct 04 02:59

There is actually a good technical reason why the Toyota gauge works(?) in the way that it does........





....but no-one here has ever had it explained in a way that makes sense.

Dave Mason's Mod makes the gauge more useful to the average 'joe' even if it is 'technically' not as accurate. And the alarm is a great additional idea.

(And before anyone asks me to explain why the original Toyota gauge set-up is technically better - I have no idea, but someone tried to explain it to me once, and I couldn't see how it was better? Yet from a 'technical perspective' it is - not better in the real world though!)

signed (the technically confused) Dave.

- (#13721) DaveW, 13 Oct 04 13:21

My view is that is might be better, considering it's original purpose, ie, being fitted to a Townace. I do think that Toyota, who could hardly be accused of fitting inferior components, "married" the gauge, to the Townace, because the vehicle was intended to be, just that, ie, a town vehicle which was never intended to perform on motorways at, or above, the local legal limits. We have had numerous postings about overheating following a 90mph blast on the motorway and, apart from the vehicle, with it's relatively small engine, not being up to this treatment, I think that the cooling system, cooling air access, and the operating range of the gauge, just cannot cope with these extremes. It seems that there is just not enough leeway between adequate running temperature and overheating. If you keep the original gauge, and assuming that all other areas of the cooling system are in good order, the 100KPH bleeper is a worthwhile fitting. If you isolate this device, and intend to keep up with the V6 Galaxys on the motorways, you definitely need Dave Mason's audible alarm

- (#13721) John Davis(Leics), 13 Oct 04 14:02

Have heeded all advice and ordered a DM temp alarm. Also new sender from my local factors - £7.50 compared to nearly £20 for Toyota unit. There's a difference between profit and profiteering !!!!

- (#13721) gordon davies, 13 Oct 04 15:11

Yes, I'm sure Toyota designed the temp gauge carefully, like everything else. I suspect that they assumed that radiators, hoses, thermostat etc would be inspected and replaced regularly in the orderly Japanese maintenance schedule for a top-of-the range limo. 15 years later our usual approach to a budget MPV is understandably different.

It's misleading to call the Mason gadget an "alarm" because its primary function is a slight modification of the way the gauge reads to make it useful in our situation. The settable audible alarm is its secondary role.

The modification is so fine that different versions are required for old/new shape Townaces - presumably because of what's fitted rather than just the shape! Substituting a non-Toyota sender may affect this fine tuning. Let us know, Gordon.
- (#13721) Dave Mason (Sussex), 15 Oct 04 03:07

During head gaskt change I accidentally broke the temp sender - fitted non-Toyota replacement. At the same time I fitted the DM device. I now find that the temp guage reads between 75% and 90%, getting close to the Red section on long hills etc.just a bit disconcerting !!! The alarm is set at 4.25.On 4 or less it has gone off occasionally. The engine doesn't seem to be running too hot, so I am wondering if the spec of the replacement sender(presumably an RTD) is slightly different to the Toyota one, hence causing a slight "error" in the guage reading.What should the signal from the sender be when engine is running at ambient, and normal operating temp - presumably it's a change in resistance.

- (#13721) Gordon Davies, 31 Oct 04 18:01

Gordon, disconcerting as it seems at first, I think you've actually got a good result.

The tendency for the gauge to "stick" near the middle is a feature of the way the gauge is built (not the sender) and in order to get the reading to change with small variations in head temperature it has to work in the right-hand half of the scale, avoiding the oddity near the middle.

Yes, this does mean the pointer gets closer to the red section without the engine actually being any hotter, but you do now know a lot more about how the engine temperature is changing. You'll soon make up your own mind where the pointer sits under normal conditions, cruising or climbing - maybe just below the red or even just into the red.

- (#13721) Dave Mason (Sussex), 1 Nov 04 01:02

Phew !! Wasn't sure if t'were me or the engine that was beginning to sweat a little.Your reply saved me the need of taking a cold shower!! Thanks again.

- (#13721) gordon davies, 1 Nov 04 13:53