Temp and fuel gauge bouncing - PeachParts Mercedes-Benz Forum

erickson13455 · #1 07-17-2008, 08:35 AM

Hi all, I am new to this forum, and my new 1983 300d turbo.

I had a strange experience with the fuel and temp gauge bouncing around. I've had the car about a month now. At first everything was normal. I was cleaning up the engine to find some leaks, and the next day the fuel and temp gauge started bouncing around. I was really low on gas, actually I think the reserve tank was used, it started chugging and a bunch of black smoke came out for about 10 seconds. Anyways I filled up this morning and to my surprise the temp and fuel gauge were solid the entire way to work, no movement at all. Well, the temp rose slowly as I was driving.

Has anyone experienced this. Is that little triangle light next to the R for the reserve light, low fuel?

Question 2- What is the normal operating temp of these cars? The car was around 100c at the end of my 10 minute drive to work, only about 60f this morning. Is that to hot? It seems I have read 80c is about right.

Question 3- I think the antifreeze is a very watery light green. I have bought some prestone, ?dex-cool?, orange cap, to fill with once a new thermostat gets here, is this an OK antifreeze, I've read I need a certain type of coolant, free of certain things.

Thanks in advance for all the replies.
Bob

ImBroke · #2 07-17-2008, 08:52 AM

Welcome!!! We're here to help.

Gauge symptoms are a bad ground. Generally associated with the cluster, but it's possible to be in the engine compt somewhere.

Yes the little triangle is low fuel. Mine comes on when I have 4 gallons left, yours may be slightly different.

Normal temp should not be 100, more like around 80-85.

While light green is better than orange (Death Cool), the proper antifreeze is either Mercedes brand, or Zerex G-05. It's a goldish color.

Welcome again, enjoy your stay, and remember the search function is your friend, you'll find tons of information.

erickson13455 · #3 07-17-2008, 09:07 AM

Zerex, G-05, I did read about that and I couldn't find any at the part stores, Oreilly, Checker, wal-mart, or Farm and Fleet store around me. Is there anything that is similar? I haven't tried the NAPA across town. What makes zerex better? Phosphate, Nitrate free??

Thanks,
Bob

cphilip · #4 07-17-2008, 10:16 AM

My temp gauge jumps around some too. And commonly shows a 100C reading.

I have, so far, replaced the Thermostat, the Radiator (for the nipple leak), Gauge sender and the Recovery tank cap and it still does it. Theres were things I wanted to do anyway or needed to do (all but the sender which was a diagnostic move)

Shooting it with a Infrared thermometer shows it is actually running no more than 91C when it shows 100C so I know now for certain it is the gauge. Either the ground or a faulty connection or solder joint.

I would recommend shooting the real temp with an Infrared thermometer to see if its is actually reading correct or not and go from there. It likely is the Gauge but this will help you decide that.

However, some manuals say the normal operating temp is as high as 95C. Although the thermostat starts opening at 80C it is not fully open until around 90C from those references. So I think a range of about 85C to 95C is fairly normal range in Hot weather and after full heat up. I also would not be too concerned with a real 100C in Hot weather with AC running etc. if thats all it did get too. But finding out what it really is and not trusting the gauge is probably the best first move.

SD Blue · #5 07-17-2008, 10:32 AM

Quote:

Originally Posted by erickson13455

Zerex, G-05, I did read about that and I couldn't find any at the part stores, Oreilly, Checker, wal-mart, or Farm and Fleet store around me. Is there anything that is similar? I haven't tried the NAPA across town. What makes zerex better? Phosphate, Nitrate free??

Thanks,
Bob

Bob,
Most folks have found Zerex G-05 at NAPA or Pep Boys. From what I have read, here on the forum, the base chemical compound is what makes it different from the green/orange types.

cphilip · #6 07-17-2008, 11:15 AM

It is a HOAT. It also is a Low Silicate. It apparently has properties (or additives? not sure which as they do not explain) to fight Cavitation (although I don't know what they are) which eliminates the need to add SCA's.

The others are either no Silicate and/or OAT's. And have no Anticavitation additives or properties in them and would have to be adjusted for that.

thats about all I have been able to figure out so far.

Jeremy5848 · #7 07-17-2008, 11:25 AM

The purpose of the "correct" antifreeze is to be kind to the aluminum parts that come in contact with the coolant. If you can't find the Zerex stuff, you can always buy factory coolant from a dealer (about $20/gallon). The factory coolant is more important in 60x engines that have aluminum heads (you have a 617 with a cast iron head).

erickson13455 · #8 07-17-2008, 12:08 PM

I'll stop buy the NAPA store and look for Zerex, any other brand that is the same as Zerex?

I did buy some 10W40 delvac?, I need to get filters at NAPA, so I can get Bosch oil, and fuel filters, is that what I want to get?