Fastback's cars.

Please post pictures, specifications and worklogs of your cars in here.

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mercedade
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Re: Fastback's cars.

Post by mercedade » Mon Jun 14, 2021 2:25 pm

scoobyh123 wrote:
Mon Jun 14, 2021 10:20 am

Adrian - i've just answered your final query on the other thread, about the blue wire, not sure how i missed your query but apologies for that!

Using a switch on the blue wire to bring the relay on will preserve the fan on with A/C as well.
Dave, I'm not sure you missed anything at all! Useful info though, cheers
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Re: Fastback's cars.

Post by Fastback » Tue Jun 15, 2021 4:56 pm

I have been further investigating the fan problem today and I believe the issue to be the thermal switch. I undid the clip and inserted an opened ended spade connector and hey presto, the fan works.

Image

I'm sure that switch is only about four years old, so I don't know why it has failed so soon. I assume the resistance value should get to zero in order to activate? Still, I shall get another and we'll see.

But if I was to fit a manual switch, that's where I'd do it. It would be very simple to run a short cable with a switch to that terminal (although actually getting into the cabin might be the hardest thing) and use all the existing wiring of the car.

I have also ordered a relay holder but it was slightly harder to find one because most 30A holders just use 6.3mm connectors. The high load ones on the fan relay need 9.5mm with two 6.3mm for the activation. I think I'll will have to cut the existing one off and perhaps mount the relay slightly lower to compensate.
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
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Re: Fastback's cars.

Post by Fastback » Tue Jun 15, 2021 7:41 pm

And the next question is, 'can I use ADU 7161' (now GTR 185), which according to Rimmers is not for the 800 petrol turbo but is for the 600 petrol turbo? Is it not essentially the same engine with different gearbox ratio?

And if not ADU 7161, then what is the part number? Unfortunately my EPG seems to be not working right now, so any suggestions welcome. Thanks
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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Re: Fastback's cars.

Post by scoobyh123 » Tue Jun 15, 2021 8:24 pm

The 620Ti might use the same engine Mark but i'm fairly sure the radiator is different. I'm having trouble connecting to Rimmers at the moment and although i still have internet, it's s--l--o--w and my landline is down.

I think you'll probably need CDU1490SLP which is the lower temperature switch (i think) on the n/asp T series but it might be the KTP9017 which is the other one.

I managed to find those before my current internet problems, hoping this reply makes it through cyberspace! :wink: :D
Cheers,
Dave

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Re: Fastback's cars.

Post by Fastback » Tue Jun 15, 2021 11:22 pm

Those part numbers look like they relate to switches that might fit in a radiator rather than the thermostat housing.

Following on from the TD5 discussion, would this work;

https://www.jgs4x4.co.uk/discovery-2-td ... re-sensor/

And ultimately (showing my ignorance here) what is the difference? I'm guessing it's the point at which they activate but if it's a little bit lower than the 98deg (then down to 92 degs?) as specified, is that a huge problem?
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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Re: Fastback's cars.

Post by scoobyh123 » Wed Jun 16, 2021 12:11 pm

Fastback wrote:
Tue Jun 15, 2021 11:22 pm
Those part numbers look like they relate to switches that might fit in a radiator rather than the thermostat housing.

Following on from the TD5 discussion, would this work;

https://www.jgs4x4.co.uk/discovery-2-td ... re-sensor/

And ultimately (showing my ignorance here) what is the difference? I'm guessing it's the point at which they activate but if it's a little bit lower than the 98deg (then down to 92 degs?) as specified, is that a huge problem?
I thought you were planning on using the holes in the rad for the new switch Mark? The unit on the 'stat housing isn't a switch, it's a sensor for the fuel ECU and reads varying resistances. It's an NTC - Negative Temperature Coefficient - thermistor inside which means as the temperature goes up, the resistance drops. Shorting it out would tell the ECU that the engine is about 1000C so definitely needs cooling! :shock:

The item you've linked to is a sensor, not a switch, you don't have a switch on yours for the fan. The coolant temperature sensor (CTS) tells the ECU how hot the engine is primarily so it alters the fueling (richer for a cold engine) and at a certain point, will put an earth onto the blue wire on the fan relay control.

Simplest way of doing things is to use a thermoswitch in the rad, one side to earth, other side to the blue wire on the relay.

You could try a new CTS first to see if that gets the ECU to bring the fan in but i know many others have tried this and the ECU still doesn't recognise that the engine is hot/overheating.
Cheers,
Dave

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Re: Fastback's cars.

Post by Fastback » Wed Jun 16, 2021 5:08 pm

Yes, my use of the word 'switch' is both sloppy and inaccurate.

What I meant to say, as I understand it, is that sensor is the trigger, ie when it gives out low resistance to the MEMS, the relay is activated, switching the fan on. In fact, just disconnecting the plug activates the fan. I have found this table with approximate values which roughly coincide with values I have measured.

Image

I got a reading of 230 Ohms and the fan still hadn't activated. At what value should it? Activating the fan, the value increased to a stable 380 Ohms.

My preference is always to put something back, or as close, to OEM as possible to avoid future confusion and forgetfulness. So if I can get this working as it as it should, then so much the better. The 'in rad' option would be a last resort. However if I can't find the correct CTS (can't even find the right part number), then the last becomes the first.
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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Re: Fastback's cars.

Post by scoobyh123 » Wed Jun 16, 2021 6:18 pm

I don't suppose you happen to know the exact temperature of the engine when you were taking those readings? I use an IR thermometer to double check if i'm ever checking anything like that.

If you buy some resistors say 220, 180 and 150 Ohms (you could alget 120 and 100 Ohms too) and use those in place of the sensor in the connector to find out what resistance the fan switches on you can work out if the sensor just isn't getting there (their resistance gets higher with age so they think it's cooler than it really is, same problem occurs with the Climate Control) or if the actual temperature isn't as high as the guage shows. Might be an even simpler solution that you need to change the guage sensor and there's nothing wrong with the original fan control system.
Cheers,
Dave

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Re: Fastback's cars.

Post by Fastback » Wed Jun 16, 2021 11:29 pm

Unfortunately, no. And I realise that without accurate temperatures, I am only a little further on, just in the ball park. What I can say is the temperature guage hadn't really started to climb (I suspect that works correctly), it wasn't above half way so perhaps the system was not under enough stress to give lower resistance needed to trigger.

I like the idea of using known resistance values to test and I'm on it...
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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Re: Fastback's cars.

Post by scoobyh123 » Thu Jun 17, 2021 11:44 am

I use one similar to this Mark :

https://www.ebay.co.uk/itm/224485565355

Mine has a PP3 battery rather than two AA cells as this one is listed as having. For the relatively small cost, even if you bought a dearer one it's still a worthwhile investment.

If you could get your engine up to the temperature where the fan comes on and measure that against the Temp guage and confirm the operation with resistors and the resistance of the CTS at the same point you should make some headway to resolving it all.
Cheers,
Dave

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Re: Fastback's cars.

Post by Fastback » Mon Jun 21, 2021 5:56 pm

Following Dave's idea, I armed myself with a few diodes to see where the resistor kicks in the cooling fan. Started at at 220 Ohms, no effect; 180 Ohms no effect; 150 Ohms fan kicks in. So it would appear the working value is somewhere 150-179 Ohms. I tried running the engine and taking readings but at 173 Ohms I chickened out because the engine was getting really hot and the temp guage suddenly climbed to very near red :shock: . Makes me think that the correct value is closer to 180 Ohms than 150.

Obviously, I am reluctant to drive the car as is, so with a friend who has electronics knowledge, came up with an idea. I dare say some people won't like it, but it is an easily reversable stop gap measure until I can find information on the OEM resistor and values. What we did, after some maths, is to fit another resistor in parrallel (as opposed to in series). This changes the values for the overall circuit and whilst other things could be affected (fuelling, etc), my main intention is to stop the engine melting. We ran the engine to get hot enough for the fan to kick in, which it did :) , and left the car running until the fan switched off, which it did :D . Not totally sure of the resistance values but we reckon somewhere in the (equivalent) 190-200 Ohm region, so cooling might start a bit early but I'm happier about that than not at all.

If anybody has a working EPC and can throw a part number at me or tell me that fitting a GTR 185 is a REALLY bad idea, it would be highly appreciated.
Last edited by Fastback on Mon Jun 21, 2021 6:57 pm, edited 1 time in total.
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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Re: Fastback's cars.

Post by Fastback » Mon Jun 21, 2021 6:11 pm

I also decided to tackle the very dodgy fan relay connection;

Image

As you can see, not great :roll: . Arming myself with a new holder and spades,

Image

set about rewiring it. Had to cut about 30mm back on all the wires but this is much better.

Image

Still not happy about its mounting point though, I think it's vunerable to a lot of weather coming in round the headlight, so I decided to fabricate a little 4 sided aluminium box to shield it from the worst of the elements.

Image

Fitted,

Image

Hopefully that will help keep most of the moisture off and at some point I'll spray it black or red.
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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Re: Fastback's cars.

Post by scoobyh123 » Mon Jun 21, 2021 6:41 pm

Your friend has done exactly what i was going to suggest as a stopgap Mark, in fact it might even become permanent with no ill effects. Top job!

The combined value of the sensor and the resisitor in parallel will be (R x Sr)/(R + Sr) where R is the resistor you've added and Sr is the sensor resistance.

Either way it will be lower than 173 Ohms to bring the fan in so let's say that the combined value is 160 Ohms. If the Sr = 170 Ohms, combined value is 160 Ohms, you can rework the equation and substitute those values or use an online calculator and this will generate a value for R of 2.7kOhms.

https://www.omnicalculator.com/physics/ ... l-resistor

Looking back at the chart you provided earlier of resistance values for engine temp :

Image

At 20C the value is 2500+/- ~10% or 2200-2800 Ohms. Let's make the maths easy and call it 2.7k so with the resistor in parallel, the combined value will be 1350 Ohms. That equates to just under 30C so not far out.

However when the temperature gets down to 0C, the sensor should be 4800-6600 and with a 2.7k in parallel will be 1700-1900 Ohms. This equates to an engine temperature of about 22C so you may experience cold start problems in winter.

Looking up the CTS (for the ECU) in the Intermotor webcat, it comes up with 55150 for the 2.0 turbo (in fact all 2.0 models from 1991 on i.e. Mk2) and then entering GTR185 :

Results Found: 1 for gtr185

Competitor Competitor Name Intermotor Part Number
UNIPART GTR185 55150

From that i'd say you were perfectly safe using a GTR 185 or if it's cheaper, an Intermotor 55150 :

https://www.ebay.co.uk/itm/254798642169

For under a fiver delivered, worth a try! :wink: :D
Cheers,
Dave

'02 Honda CR-V SE Executive
'99 Jag S Type 3.0 V6 SE


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'94 827 Sterling saloon
'88 Volvo 760 V6 Estate
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Re: Fastback's cars.

Post by Fastback » Wed Jun 23, 2021 7:49 pm

I've done some further investigation regarding the CTS by referring to the Rover workshop manual. Interestingly what it is suggesting for the 96MY on is;

Image

As you can see, it lists the GTR 185, which is counter to what the EPC says, certainly on Rimmers at any rate. Who was it who said, 'Rimmers spreads only confusion'? Not sure it's their fault to be fair but if they left all the parts on as a source of reference it might help.

The goods news is that that sensor is freely available and one is on its way. I'll test both values of the mod and the new sensor, just for interest and comparison.
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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Re: Fastback's cars.

Post by Fastback » Tue Sep 07, 2021 3:31 pm

Good to read of other folks' trips, jollies and successes.

I've been a bit quiet but still plugging away. Both cars through their MOTs but the Sterling with advisories annoyingly, I thought I had them all. Bit of peculiar tyre wear on the Sterling fronts , both nearside edges are near limit (camber wear). I will have the tracking checked before I look at anything else, eg track rod ends etc.

I mostly fixed my air con, a front pipe had bent and leaking at the connecting block near the radiator, had it gassed with a dye and for ten weeks, nice and cool. However, that stopped and the dye/R134A is leaking from an 'O' seal on the compressor. But today I notice the compressor, nor the fans are working, even after I put a bit more gas in (was ¾, now up to the lower edge of full). Haven't checked anything yet but I'm a little upset because it was working :cry: . Is there a self diagnostic other than for the sensors?

Could really do with it, what with the glorious weather we have right now!
Mark
'99 Sterling KV6 Fastback :D
'96 Vitesse Lux Fastback, rolling resto :?
'96 825 SLi Fastback, just waiting. :|
Previous:- 'J' 820Si Fastback, part Tickford
MG Maestro 2.0i (I loved that car, I did)

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