Question on Temperature Gauge Reading

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22 Jun 2011 07:41 #5211 by EWM
Hello,

I am new to 928s and new to this forum and I have an immediate concern about the car.

What temperature range is acceptable for a 79 928 stopped at a traffic light on a hot afternoon with the air conditioner running?

The temperature gauge indicates ¾ of the way towards hot and then slowly falls down to just over ½ of the way when the car is moving. The coolant level is fine. Have not had time to look at the radiator fans with the car running.

Is this a normal temperature reading?

Thanks,
Woody Montier

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22 Jun 2011 08:39 #5212 by adminVB
Replied by adminVB on topic Question on Temperature Gauge Reading
I have moved this to the appropriate forum, technical discussions.

As I recall the '79 will have a fan that is belt driven then fluid driven.

With the engine *OFF* see if you can spin the fan easily. If so, then it needs to be refreshed or replaced.

When you are moving the air flow is usually sufficient for most cooling needs, so it is likely a fan issue.

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22 Jun 2011 11:24 #5213 by EWM
Thank you for the tip. It makes sense becasue I can turn the fan blade by hand easily. The blase does not spin from a flip of the wrist but there is not much resistance.

Do I rebuild or repalce the fan clutch? Is there a recommeded parts supplier?

Thanks again,
Woody Montier

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22 Jun 2011 12:01 #5214 by srshaw3
There is a backyard type of fix you can try: www.nichols.nu/tip482.htm

You might be able to get a good used replacement from 928srus.com or 928intl.com, they both might have other options and suggestion on how to fix as well. 928gt.com would be another source for new parts as well.

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22 Jun 2011 15:39 #5219 by pcar928fan
Many remove the viscous fan altogether and upgrade to full electric fans... Not cheap, but not overly expensive or difficult. That gauge is not calibrated for a reason...each car is a bit different (actually on the GTS's they are calibrated and maybe on all the '89 and up cars even). It does not sound like your car is overheating and not getting dangerously warm either...

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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22 Jun 2011 19:18 #5222 by EWM
Thanks for the information. I will try the clutch repair with silicone oil. And if that goes wrong, an electric fan will be an option.

Is there any preferred electric fan known to fit?

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22 Jun 2011 20:17 #5223 by srshaw3
If you check with the vendors I mentioned, and perhaps 928motorsports.com as well, they will know what the options are. To some extent it becomes a judgement call on what you find right for you. You can certainly ask here if anyone has one of the products out there offered and how they like it, or if they developed their own fan.

When I was racing, I just got a puller fan and mounted it on the inside of the radiator, basically it was just a matter of determining what CFM I wanted and was available in a size that would fit. When you removed the current fan you will have quite a bit of room :)

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23 Jun 2011 15:43 #5226 by EWM
Contacted the previous and original owner. The 928 reportedly has always run with the gauge 3/4 toward hot when idling with the A/C on. And runs 2/3 towards hot rolling down the highway.

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24 Jun 2011 14:41 #5240 by N2O-928
I think that a 2/3 reading is high on that year car, no more that 1/2 unless something is not working corectly. Get a real Infra red temp meter and check it out.

As far as the fan's go, the belt driven fan should only spin freely (engine off) when cold, when hot (eng off) it should show resistance (else it won't work) to pull the air. Should be able to get a used one form 928international.

The electric fan should come on for three reasons:
1. by the temp of the radiator when it gets about 2/3 on temp guage, this is controled by the switch on the lower left side in the fron on the rad.
2. When the AC/ is on and the A/C Drier get to high (from heat in the A/C).
3. Intake air temp switch may depend on what year.

These stock systems work realy great and do not over heat if everything is working corectly, also please make sure you are running 50/50 antfreez/water and add a can of water wetter

Dave

PS: I do agree that all of the gauges do vary and most of the newer '87 and up seem to run at 2/3, but the pre S4's not so much.

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29 Jun 2011 19:26 #5319 by Sweet928
My '79 ran at bottom third of the gauge since I got it. I just had it serviced (With major thanks to this fourm for helping me finally find 928 mechanics in NJ). Turns out I needed a new temp sensor and now gauge runs at just below the half way mark. My '80 also ran around half way range too. Fans kick on when it's hot out.

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29 Jun 2011 22:14 #5324 by mm928
My 83 runs at 3/4 when hot and a little below 3/4 when it cools off. This has remained consistent even with the 90+ degree temps so far this summer. I believe this is pretty common on the older cars. As for electric fans, check out 928 Specialists. They have a twin fan SharkBlade setup for about 450.00 which seems fairly easy to drop in. I am thinking of doing that as an upgrade later. I really have no overheating problems running at 3/4 right now, just would like to improve it.

Update from Oct 2011:
I put in 2 new 75 degree centigrade thermos, one in the engine of course and the other on the driver's side bottom of the radiator. That one controls when the outside fan kicks in. You should replace them both so the work together and bring the cooling on at the same time. Since I have done that, I run a little below middle to slightly above if I am blasting (like on a Fun Run with other 928's through the mountains). So it has helped tremendously and was relatively cheap. It also helped fix a heat-sinking problem I was getting after I turned off the engine. It would not start for up 1 1/2 hours like that unless you did it in about the first 5-10 minutes. Problem is now solved. Might be wise to replace the thermostats if they have not been, and if you are inclined, use the 75c ones instead of the stock 83c ones. 928 Spec or 928 Motorsports etc. have them

This may help if your outside fan and inside fan are not really pulling their weight right now and a lot cheaper than replacing both. You have to be careful with the electric fans on older 16v cars. They do not have the juice of the 32v'ers. If you have a strong electrical system and are putting out good consistent power, like 12.5 to 13.5, then you might be fine. But read the specs on what you are adding to what your electrical system (especially that model year) was designed for. Good luck

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -

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30 Jun 2011 01:01 #5328 by 928mac
My 89 runs between 1/2 and 3/4

Here is a Rennlist link on a cheep fan mod

forums.rennlist.com/rennforums/928-forum....html?highlight=fans

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04 Jul 2011 15:37 #5412 by mm928
I have an 83, and it runs just below 3/4 most of the time, if it peaks over that it is only for a short time (I assume the cooling mechanism works). It seems very consistent.

So for me what you describe appears pretty normal. I never get it down to 1/2! I am going to get the dual electric Shark Blades I think later this year or in the spring of next year.

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -

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