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Discussion Starter #1 (Edited)
3.0 PH1 1998

changed last year radiator, But more recently given the rad a Wynns Rad flush and new coolant


Replaced

the coolant cap
thermostat
clocks for the temp gauge on center console
temp sensor on the rad
2 temp sensors on the thermostat

Thermal probe reads the fans come in around 93 and switch of around 88, had 2 sets of clocks and both the same temp reading on gauge and 2 thermal probes and both read the same temps when measured on the metal thermostat housing

So my problem is false reading going to the temp gauge


Just had a new condenser for the ac so all the veins are perfect condition to allow air through the condenser onto the radiator
 

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Does the car report the same temperature with the engine running ( fast idle ) and with the engine off but ignition on?

Have you connected a diagnostic to the engine ECU to see what the engine ECU is reporting as an engine temperature? The radiator is a bit of a red herring as it is measuring the temperature of the water at the rad. Not the block. Connecting a diag tool may show that the temperature gauge is reporting faithfully and the engine is actually running a bit hot. Also, if you have an IR thermometer or a thermocouple on a multimeter, measure the temperature of the metal around the thermostat.

If you do have a multimeter, disconnect the two temperature sensors on the engine ( forget about the the thermal device on the radiator - that only controls the fans ). Measure the resistance across the two sensors with the engine cold and, if you can avoid injury, with the engine hot. In both cases the multimeter readings should be about the same. With the engine cold ( at ambient temperature ) I'd expect to see readings of around 10K Ohms ( maybe slightly higher as ambients are a bit less than 25°C at the moment ). With the engine hot, I'd expect readings in the low hundreds of Ohms.
 

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Discussion Starter #3
My car has a old style 3 pin diag socket and i cant find any specialist who can make a connection unfortunately


with the engine running it reports a temperature on the gauge and then when i turn the engine off it returns to the lower point stop and then switch ignition on it returns to exactly where it was on gauge when engine was running


the probe was measuring tems both touching the thermostat metal housing and the radiator metal both very similar temps, My Alfa garage reported with there probe similar temps to mine

In terms of the 2 sensors they are below the thermostat housing and are hard to get access to because of heat and poor visibility, from above you have to dismantle a fair bit of the induction pipework in order to see them dont thing from below will be any easier,

I guess your instruction was to test wiring irregularities and dont have the means to avoid burning my self to carry out the test,
 

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If you unplug the connector to the gauge temperature sender and connect the grey/green wire to the thermostat housing with a resistor (220 ohm).
In this case the gauge should show approx. 90°C independed of the actual engine temperature.
If you connect the grey/red wire to thermostat housing the over temperature light should be on.

If the gauge shows approx. 90°c with the test described above I would say the temperature sender is broken or the engine is actually running at a higher temperature.

The resistance of the temperature sender should be the following:

60°C: 525 - 605 ohm
90°C: 194 - 245 ohm
120 °C: 82 - 94 ohm.
 

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Hi brad,I'm having the same problem with my 99 2.0 gtv.temperature gauge almost at max,but the ecru reading normal 88 degrees,cooling fan comes on as normal,changed everything twice.new rad,thermostat,temp sensor-x3.gauge x2 and waiting on another set of gauges to test.hope we can find the answer?
 

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I've found with testing, the gauge mirrors the ECU exactly and in my case the fans kick in about 94°. Does the gauge zoom up to that temp or is it slow. Mine takes an age and the fans only kick in when stuck in traffic for a while.
 

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Discussion Starter #8
mine rises slow (around 10 min of driving) and the fans also kick in around 93 taking the temps down to around 87 before switching off when measured with a thermal probe onto the metal thermostat

even changed the header tank cap GGRRRRR
 

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There are many different part numbers for the gauges on eper. No idea what the difference is between them but might be worth putting in your chassis number and seeing what part you should have.
 

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Discussion Starter #10
Well when i had the old clocks out and the new (old) clocks ready to put in i could not find a part number on either, I thought PH1 style was all same ??
 

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It might be worth checking all the relevant earthing points for the engine, battery and clocks. On a previous (non Alfa) car the gauge started to read high but everything else suggested temps were normal. It turned out to be corrosion between the earth cable and the battery clamp which was not visible but on checking the voltage fall along the battery cable it was obvious something was wrong. On replacing the battery earth cable all was back to normal. It would seem the resistance in the battery earth cable forced the other engine earths to take an increased load (especially through the temp gauge lead) which was not ale to cope with the current and in turn heated that cable which increases the resistance and gives an artificially high reading. Worth checking out.
 

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Discussion Starter #13
my to do list has never ever been empty, This is encouraging by your comments and your fixes i will have a look
 

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Discussion Starter #14
If found the problem.I bought an original temp sensor,all's back to normal.hope this helps
Snoodles just so i know..................... are you saying you had a generic after market one in there that you changed as part of your attempted fix or was it the original one in there ?????? and you went straight for the new alfa one ??

was it a brand new alfa one that you purchased ???
 

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Discussion Starter #15
Is there a bleed valve ???? or bleed method, Obviously recently had new coolant as part of process to find solution, Someone suggested i may have an air lock ???

do these self bleed ??? been running the engine over 150 miles now and i guess its all gone round system a thousand times but could there still be air block ??
 

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Just run it with heater control set to hot and remove cap off header tank. Wait till it comes up to temperature and top up if necessary. Put cap back on.
 

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Hi brad,i bought and original Alfa Romeo sensor from alfaworkshop.as soon as I put it in the temp sat at a solid 90 on the gauge.the sensor that was in there sat the gauge at 3/4 the way up.then the generic(can't remember the brand)sensors just made the gauge rise to max.anytime I will be buying electrical parts I'm going original Alfa parts.
 

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Discussion Starter #18
Snoodles....................... thank you for your important information, Mine is Cambiere VE718062 in there at the moment (well it sounded Italian) and i think i will follow you and make sure its Original Alfa


Try bleeding it first just to see
 

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Brad I have the original sensor that's was in the car that was faulty and it was giving a better reading than the 2 new sensors which are FACET and another brand that I can't remember.the original Alfa Romeo sensor that I bought on Wednesday came in an Alfa branded box but didn't have any Alfa branding on the sensor its self,really hard to tell apart as the look exactly the same.from now on I will be buying Alfa original,although a bit more expensive,better than buying loads of other after market ones and still having to buy one of Alfa,plus if it hasn't solve the problem you can confidently rule it out.hope you get it sorted.
 

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Discussion Starter #20 (Edited)
Alfa Workshop say there are no longer Alfa Originals (for my chassis number ), They use FAWCET also in there service department and they are Alfa specialists, My choice usually is Alfa or failing that Bosch, But in this instance i could find neither when i went searching with a part number for my car
 
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