(Home) mason alarm

I have just fitted Dave mason's temperature alarm which is working fine on short journeys, reading just above half way on the gauge. The only problem is at speed over 60mph up hill the gauge goes into the red and alarm sounds. Then goes back to normal on a level run. Can anyone suggest possible causes?
Thanks
Mal

- (#1068) Mal, 2 May 05 15:58

Well, the alarm you could turn down a bit, but the gauge heading into the red is a bit worrying. Has the cooling system been flushed recently? Is the thermostat in good condition? If it's yes to both of the above then I'd guess on a faulty fan coupling. Take it for a hard drive with the seat raised and watch the fan- you might see it slowing or stopping when driving at high speed...

A long shot is that the engine etc is OK and the problem is with the temperature gauge sender...

- (#1068) David Miller, 3 May 05 00:25

If you disconnect the alarm, just undo one of the wires in the multi block within the alarm unit no need to remove the dash again, and then do a similar drive to one that reached the red. If the guage, which is now at pre alarm installation state, stays as it allways did then you do not have a problem. Re connect and set the alarm trip a little higher.
Don't forget the guage has been modified.
There is the remote chance that you have the wrong alarm unit for your setup, I'm sure Dave Mason will be in contact with you.

- (#1068) Clive (Bristol), 3 May 05 02:06

To clive and Dave Miller
Thanks for the advice managed to take it out for a run today under same conditions except this time with the seat raised high revs at speed did'nt notice the fan stopping or slowing down but did notice no matter how hard i drove the modified gauge would'nt go into the red like before but as soon as i put the seat back down and went up hill the gauge went into the red , 19 dot, alarm is set on 4.5 on the trip. Any ideas.
Thanks, Mal

- (#1068) Mal, 3 May 05 15:18

Sounds like the cooling system is (pardon the pun) running out of steam... Airflow through the rad is increased when you have the seat up, so it sounds like you're a little short on cooling capacity. I'd definitely recommend a check of the 'stat (is it by any chance a cheapie, rather than an OEM toyota one) and giving the rad a backflush.

When the gauge is reading high, can I presume there's no gurgling or steaming at the expansion tank?

- (#1068) David Miller, 4 May 05 01:55

Yes, the thermostat could be where the problem lies. Although I have not got one of the Mason alarms,I had fitted a Durite gauge before Dave had developed his device, and I was able to see, much more accurately, the changes in temperature, especially under load on hills. Almost four years ago,I followed David Millers advice and experimented with the thermostat, ie, by fitting the genuine Toyota type, which has a 30mm opening instead of the pattern type which, I think, has only a 25 mm opening, and modifying it with a series of "bypass " holes in the thermostat flange. I run a summer stat with three 3mm bypass holes in the flange, and a winter stat with just one 3mm hole. With all the other checks done, ie, viscous coupling, integrity of hoses, correct rad filler cap and secure expansion tank vacuum hose, I have never had any problem and the Durite gauge, very rapidly, shows the rise and fall of the coolant temperature, unlike the old Toyota gauge, which did not. The archives show the discussions of the thermostat modifications and, in my opinion, the increased coolant flow, which these modifications allow, is the key to improving the cooling capacity of a vehicle designed for an around town life but, in this country, has to perform in more arduous conditions

- (#1068) JJohn Davis (leics), 4 May 05 02:46

I hope these comments don't sound defensive because I don't feel I need to be ...

"into the red, 19 dot, alarm is set on 4.5" sounds as if it's not the wrong alarm unit, Clive, because, as requested, I supplied the type for a gauge with dots rather than a line.

The mod. is meant to send the instrument into the red when the sensor gets very hot, and 4.5 out of 6 on the alarm level adjuster is about right for this condition. On balance it sounds as if the fault is in the car and the temp gauge mod has revealed it rather than the fault being in the "mason alarm". I hope it's solvable with help from here.

Just in case anyone's wondering, my policy is to work with customers to solve problems with the temp gauge mod, and money back without quibble if it's returned as "no good". In practice, out of 100 or so customers after the prototype stage, there was one sounder component that failed with an internal fault, and a couple of cases of "wrong alarm unit" - pre- or post- 1992 with dots or line across gauge. No-one has asked for a refund.

The internal 3-way screw terminal "multi-block" to which Clive refers, was only in the development prototypes and early serial numbers. I stopped fitting it because no-one ever needed to detach the cable at the device end and including it potentially reduced the reliability. So to remove the device you either have to go behind the dash again or cut and tape off the 3 wires inside my box. I can supply free-of-charge the small 3-way screw terminal blocks to retro-fit if desired.

- (#1068) Dave Mason (Sussex), 4 May 05 04:37

Sorry if I was misleading, just relating the steps I took during the field trials.

The alarm is the best add on you can buy for your Ace!

It appears that it has highlighted a potential problem that the normal Toyota guage has failed to indicate.

There will be some on sale at the Brean Ace Jam.

- (#1068) Clive (Bristol), 4 May 05 05:54

Forgot to mention i have Masterace TD 4x4 Auto G reg. Thanks to all for suggestions ,no evidence of gurgling , steaming or loss of coolant ,may have to check thermostat as advised and take it from there.
many thanks , Mal

- (#1068) Mal, 4 May 05 12:51

Just a thought about the symptoms - better with the seat up - is the big black plastic cowl in place between the upright radiator and the main engine fan?
I remember one owner reported that it was missing which make the fan far less effective.

- (#1068) Dave Mason (Sussex), 5 May 05 05:28