124 cooling system (idling & freeway)

[francis]

I have a problem with my cooling sytem. Here are the facts:

Freeway (60-100kph):
- temp at 80 degress or lower (GREAT TEMP)!

Heavy Traffic:
- temp at 100-110 degress
- I have to rev. (1500 rpm or higher) the engine during stops to prevent the temp. going up to 120 degrees
- when I rev. the engine the lowest it would go is about 100-105 degrees, but once the card start to move and maintain a constant speed of about 80kph it goes down to 80 degress or below.
- My OIL PRESSURE also drops to like 1 during idling when I hit 110 degrees.

QUESTIONS:

- Am I using the right OIL?
- Is there a relation of the cooling system when the engine is REVING high and ON THE FREEWAY? The only difference that is obvious is that when I'm on the freeway there is AIR coming through. - Is it possible that my radiator's fins or AC fins are just dirty?
- Could the CLUTCH FAN be busted?


Would appreciate the comments.


Thanks!

Francis

[stevebfl]

You are either not getting enough flow at lower speeds or do not have enough fan.

Verify the activity of your auxilary cooling fan. For diagnostic purposes by-pass the high pressure refrigerant switch and the low speed ciruit should make the fan work. See if that makes a diiference. (this of course only applies if your fan wasn't on at all). Check the your fuses as this is a common problem - the fuses expand and contract under changes of current flow and the fuse cracks.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

[francis]

Thanks for the reply! Checked the auxilliary fan asn it works. I also checked it while the car was stuck on traffic and YES, it was on.

Is there a way to diagnose the CLUTCH FAN?

How do I know if i'm not getting enough WATER FLOW during idling?

Any possible parts that could be restricting WATER FLOW at low engine RPM?

Could a busted thermostat do this?


Thanks again!

Francis
85" 300D (124) EURO

[jeffsr]

Francis,
A defective thermostat can produce this problem by not being open fully at rated temp (88-90C) This will restrict coolant flow and allow heat to accumulate. Your fan clutch should be at least partially engaged at about 90C. You can tell by bringing the rpm's up to about 2000. with a good fan clutch, you will definitely hear the fan working. If you keep it a 2000 and the temp starts to drop to the 86-88C range, the fan will begin to declutch and become quieter. Oil pressure will drop in an inverse fashion with increasing temp. It gets thinner when hotter and pressure goes down. You may have some air in your cooling system, your radiator may be partially occluded. If your aux fan is coming on and it's still hot, then something is wrong. Start with thermostat, fan clutch, air in sysem, radiator. You should be able to find the culprit. Good Luck..

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 04-09-2000).]

[stevebfl]

Yes. I would replace the thermostat first.

Judging engine flow is hard. Most of the tricks I know depend on experience for their use. One is to gently squeeze the top hose while reving to motor. If you feel the hose swell then the likelihood is that the radiator is restricted.

The fan clutch should be relatively firm when hot much more so than below its thermostatic temp. If you hold the engine at 2000rpm as the fan t-stat closes the noise the fan makes will get distintly louder as it speeds up.

Does your car have factory air? I have seen a number of non-US models with extremely small radiators not suitable for hot climates OR airconditioning.

Radiator flow/heat transfer problems are also hard to diagnose as it is a qualitative problem and judgement. I have seen many aluminum core radiators that must form enough of an insulative inner coating to not cool the motor but still flow good. Tough call, hopefully the thermstat fixes your problem.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Francis, you have gotten some good advice so I do not want to dwell on the thermostat. When I looked at my thermostat when I bought my 300 SD, I found that someone put a piece of wood in there and there was no thermostat! That is not expensive to fix.

Also, a no brainer is go to the MegaMall and get some "PEAK" antifreeze and mix 50-50% mixture. Do not use just plain water.

Also when in traffic, avoid staying too close to the car/jeepney ahead of you. The hot gas will just add to the over heating. This is of course after you have heeded the above advice.

The main keys are
1)Antifreeze or "Coolant" in the Phils
2)Fan
3)Thermostat
4)Radiator Size
5)A/C size
6)Driving Habits

I would check the above for your car in that order. You are bound to find something. It may also helpful to flush the radiator if at the end nothing is working to improve the situation.



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'89 420 SEL
'90 300 SEL
'84 300 SD (sold it)

Francis I know a good mechanic in your area.

Go to "SUNSHINE MOTORS" and ask for "Delfin". He was one of their head mechanics. He is very good. I would recommend them if you cannot fix it yourself. Tell him the "Big Kano" with the light blue 300 SD sent you. He may or may not remember me. Delfin is very good.

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'89 420 SEL
'90 300 SEL
'84 300 SD (sold it)

By the way, Sunshine is in the "Timog" section in Quezon City, just in case you never heard of it. There are very competant mechanics, I'd put Delphin on the same plane as any of the U.S. experts. You sometimes have to push them now and then because they sometimes get sidetracked, but overall I got good service at decent prices. The looks of the place is not that great, but who cares about that. Delpin may remember the tall Kano, "Matt" , I was a tough customer, but was fair.

CATS on EDSA was much more expensive.

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'89 420 SEL
'90 300 SEL
'84 300 SD (sold it)

[francis]

Thanks Matt! You still here? I know where Sunshine is. Will check it out.

I've already replaced the radiator to the TROPICAL VERSION.

Will go later and change the T-STAT. Someone recommended that we just INJECT the CLUTCH FAN with SILICONE OIL. Will this work or do I have to get a new one?


Thanks!

Francis

Walang anuman. Ako sa States nygyon. Did I say that right? ha ha ha

I might be headed back in a few months on business.

Good luck. In the event that you're frustrated, and you really need the car done in a hurry, leave it at Sunshine.

Kaibigan mo,
Matt

See. I learned a lot! he he he

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'89 420 SEL
'90 300 SEL
'84 300 SD (sold it)