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flipper687el Newbie
Joined: 20 Dec 2014 Posts: 8 Location: Spalding
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Posted: Sat Dec 20, 2014 21:14 Post subject: Temperature guage raises sharply then returns to normal |
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Hi all just bought a 1996 colorado 3 ltr diesel manual. Drove to Matlock today to pick up a new set of steel rims and MT tyres. All in the back on the way home.. Had a full service done the previous day with the MOT all ok just back box and pipe change but was aware of this. Have read all threads reference overvheating but none seem to match what I have seen today on gauge. When driving around Matlock on the way home kept seeing temp gauge rise quickly towards the red but never in the red then just as quickly return to normal state between 1/3 and 1/2 scale. Tried playing with the heating driving hard both up hill and on the flat could not consistently produce heating spike. As I say spike rises quickly then needle drops to normal just as quickly. Did not see this at all on the way to Matlock or the previous couple of days. Have checked the coolent tonight when home cannot see any signs of head gasket probs. Started from warm no signs of white smoke. Only thing I can see in coolant expansion tank is coolent looks blue. Did see a thread about coolent types not to be mixed but did not really understand. Going to get sniff test done for exhaust gas Monday.
Only thing can think is on service had flush additive added to old oil when this was changed. Also had fuel additive in a full tank of fuel for the run to run through. Water levels appear normal heating functioning normally through out range.
Any ideas or thoughts appreciated Dan. |
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Posted: Sat Dec 20, 2014 21:14 Post subject: Google Ads keep this community free to join! |
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BobMurphy Lifetime member
Joined: 01 Aug 2008 Posts: 1739 Location: Kirkliston, Scotland
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Posted: Sat Dec 20, 2014 23:44 Post subject: Re: Temperature guage raises sharply then returns to normal |
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Dan,
You are right in that it doesn't sound like a head gasket problem.
I would start by removing the thermostat and testing it in hot water - it could be 18 years old!
If it is not reacting as intended it could be causing the temp to spike. Its also the cheapest fix going so the best one to start with.
Secondly, check the viscous hub in the cooling fan. Its supposed to lock the fan hub to the drive shaft when it gets hot - but it won't get hot if the thermostat isn't opening. To be honest, at this time of year I wouldn't think the cooling fan is the culprit as the airflow will be cold enough on its own.
If you have read all the threads you will know that the thermostat is at the bottom of the block where the lower radiator hose connects .
Let us know what you find as this sounds like an unusual case .
Best of luck.
Bob. |
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flipper687el Newbie
Joined: 20 Dec 2014 Posts: 8 Location: Spalding
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Posted: Sun Dec 21, 2014 8:29 Post subject: |
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Hi Bob will do, going to have it changed anyway and a system flush.
Going to test the sensor unit today.
Do you know if the gauge goes full scale when a sensor fault occurs. |
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BobMurphy Lifetime member
Joined: 01 Aug 2008 Posts: 1739 Location: Kirkliston, Scotland
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Posted: Sun Dec 21, 2014 12:12 Post subject: |
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flipper687el wrote: |
Do you know if the gauge goes full scale when a sensor fault occurs. |
I dunno . . But I do know it goes full scale when I run out of water .
(A Roughtrax replacement head sorted that ).
Bob. |
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LJ79 *
Joined: 14 Apr 2010 Posts: 29 Location: Malta
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Posted: Fri Dec 26, 2014 21:14 Post subject: |
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I (probably) would not worry about that at all.
It's (probably) an electrical fault.
I say (probably) as an ass-saving measure of course, but I have the exact same problem if you can call it so, on my 79 series.
On this model the temp and fuel gauges are paired, and as the temp needle shoots up, so does the fuel gauge. Good news is that the engine temp is not really going up, bad news that neither is the fuel tank filling...
My local sparky who is a bit of a Toyota fan said that it's something to do with the gauge itself (a fault with the damping) and that if I wanted to sort it I needed a new gauge. Since this happens only occasionally, and for only a few seconds, I decided to live with it. Furthermore seeing the fuel gauge rise too quickly reassures that it's the usual thing and not any genuine overheating.
Anyway if your gauges are not linked, the fact that the temp rises with 3-5 seconds - as fast as the needle can rise - (impossible for engine temp to rise that fast unless cylinders filled with TNT) and that it drops just as fast, is all you need to know.
So, no worries. |
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Jet2work ***
Joined: 02 Jun 2012 Posts: 159 Location: France
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Posted: Sat Dec 27, 2014 9:09 Post subject: |
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i had a very similar thing happen to me when i first bought my 120, it turned out that the garage had had the clocks out of the dash squab, they had not reconnected the multi connector properly... before you start ripping things apart may be worth a check! |
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Trevski Lifetime member
Joined: 26 Aug 2010 Posts: 81 Location: Brackley, Northants
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Posted: Mon Dec 29, 2014 17:42 Post subject: |
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I've had this on my 90, turned out to be the old rad cap wasn't venting off, I could smell hot coolant whenever I stopped and it had chucked a small amount out from the expansion tank. Changed cap for a new one and no issues since. _________________ '05 120 LC4
'03 120 LC5
'96 GS 24v manual
'96 VX 24v manual
'98 SWB KZJ90
'95 VX 12v Auto offroader
'00 100, BFG KO2 AT
'98 SWB KZJ90 - Broken
'89 LJ70 SWB VX Turbo. SOLD |
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flipper687el Newbie
Joined: 20 Dec 2014 Posts: 8 Location: Spalding
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Posted: Fri Jan 09, 2015 20:15 Post subject: Radiator leaking from top well when pressurised above 1 bar |
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Guys had a pressure test done at above 1 bar rad was bubbling all around the top well bonding to the core. Have now fitted a new rad an stat from roughtrax so will now monitor for the next few runs. Dan |
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