Engine does not reach 80 degs

[tarmacsurfer]

Hello all, I'm new here and would like some help with a problem I have. I have a 1991 300E Sportline and when at a standstill the engine gets up to temp no problem (fan cuts in at 100ish degs, no worries there). However when driving the needle doesn't get up to 80degs and sits between the 40 and 80 deg marks?? Could it be the thermostat jammed open? My fuel consumption isn't to bad (26, 27 mpg) so I'm not sure if it is running cold or whether the temp sensor is on its way out?

I have looked at previous threads on overheating but not seen anything about overcooling...unless I'm looking in the wrong place?

Also while I'm here. at some point the previous owner has replaced the fron coil springs with what appear to be standards, ie they are too long. The car sits too high at the front and with the naked eye it looks like the camber of the fronts is positive?!? Will shorter Ventura springs work or do I have to splash out on the proper Sportline springs from the stealers??

Cheers for all you help in advance

Regards

Ben

 

[guydewdney]

for the cost I'd repalce the thermostat and see what happens.

springs - also consider changing the spring pads - they come in various thicknesses. have a look at the top of the spring - theres a rubber pad they sit on. there should be 1 / 2 / 3 /or 4 blobs - 4 = thick, 1 = thin. these are quite cheap to replace. USE A MB COIL SPRING TOOL not a std one..

 

[sebastianforbes]

hi there

if the engine is running cool, does that create a problem or raise a concern ?

cheers

sebastian.

 

[ajadams]

I don't know about your particular car but by running too cool you can fool the computer into thinking that the car has not warmed up yet, and it will add more fuel to the engine (like the choke mechanism on a carborated engine). This would cause you to use more fuel and increase emmisions.

 

[pluggers]

There has been a lot of debate about running temps before and the general consensous is that the temp gauges always read low not thought inacuracy but just because they dn mine it hardly ever goes above 82 deg only when its a hot day and stuck in traffic will it go above that temp.Weird I know but it seems just a trait.

 

[sebastianforbes]

hi there

ajadams - i understand what you're saying. but what occurred to me was that the o2 sensor in the exhaust would correct the over-consumption of fuel ?

mine normally runs at about 80. it did once go over 110 last summer in a traffic jam - i think that my viscous clutch needs replacing. in the winter on a really cold day, the engine temp is slightly lower.

btw, is the temp reading in the dash an indication of the fluid in the radiator, resevoir or the engine ?

cheers

sebastian.

 

[ajadams]

sebastianforbes,

If your car is like mine, the fan does not come on until about 90 degrees. So the temp going up to 110 would not be uncommon setting in traffic since you are not moving, air is not moving over the radiator until the fan comes on. As soon as you started moving, the temp should have gone back to normal.

I don't know how the programming in the computer is programmed, as to what the system would do with the information. I think the computer would see the o2 reading being high as an indicator of the increase in fuel due to the low coolant temp reading.

Usually coolant temp sensors are threaded into the engine block.

 

[joe bloggs]

Temp sounds normal to me especially at this time of year, i would leave it alone, as far as springs are concerned I would recommend genuine MB springs every time, too many low riders, or pogo stick mistakes out there, the correct springs are calculated on a points basis based on the equipment on your car, although there may only be one version of Sportline spring available. It will be the correct height, you can muck about with the spacers to fine tune the height if you want, they are sized from 1 to 4, with 1 being about 1cm thick and 4 about 4 cm, find the correct one for your car (dealer parts dept can tell you) and go up or down a size depending on the look you want. You can check which spacers you have by looking at the spacer on top of the spring and counting the number of dimples pointing down, can be done in place.

 

[tarmacsurfer]

Cheers one and all! I think I will leave the temp issue until it warms up a bit and then see what happens. RE springs looks like I will be going down the Dealer route.

Thanks again for all your help everyone.

 

[bruiserbruce]

my thermostat broke at 200,000K. It will then stick open and the engine runs too cool. Quick and easy to check or replace.

 

[joe bloggs]

If it aint broke don't fix it.

 

[talbir]

Sorry, but if your temp needle sits between 40 and 80 even after a few miles of driving then you HAVE a problem.

Operating temp is 90 deg C - regardless of ambient temps.

Too many people out there who think running cool is good. It's not - it's bad, very bad.

As others have suggested, replace the thermostat. And ensure you have the right mix of antifreeze in the coolant system. Too little or too muuch is bad. A 50-50 mix is fine.

On a car over ten years old, certain components of the cooling system will need replacing sooner rather than later. It's actually no harm to replace the thermostat AND radiator. Yes, rad is expensive, but cheaper than the cost of fixing problems it causes if it's bad. And renewing the coolant system water every 12 motnhs is very good practice.

Springs - yes, you can play with the rubber pads. but if you have a big gap, pads will not do the job. The pads available for the W124 range from 1 nib to 3 nib, with the difference between 1 and 3 only being approx 1.5 cm. So that's the max you'll drop the car by changing pads.

I believe there is nothing wrong with cutting the original springs. You can achieve the desired height by cutting half-a-coil, fitting back-up, drive and let the car sit, then measure up, from the centre of the wheel to the peak of the wheel arch. If it's ok, then fine, otherwise remove spring and cut another half-a-coil off. Before playing with the fronts check the rear is not the cause of the problem. It if's sagging at the rear, the front will lift. Especially if you have self-levelling suspension which may be faulty, causing rear-end sag.

And cutting/shortening a spring actually makes it STIFFER. Lots of people talk rubbish about how cutting springs makes them softer.....they haven't the foggiest understanding of physics !


talbir

 

[joe bloggs]

No, 90deg is too hot, something wrong with your car, (too close to unpressurized boiling point), normal running temp is around 80 deg, (the guage pointer should sit just below horizontal) how quickly does the temp rise to normal?, if it takes ages then yes change the thermostat, radiator confusing, as it is unlikely to make the car run cool, waist of money.
As for cutting springs, well I've heard a few in my time....apart from having the wrong end profile this can only be a bad idea, I would strongly recommend dealer springs, you will not have to worry about correct height, how could you be accurate enough, sure it will be stiffer (less coils to twist). leaving aside physics and mechanical engineering this is just plain daft, how many owners would remove their springs, stick them in the vice and start hacksawing chunks off, maybe they should soften them first..and then re-temper them.

Packers are available from 1 to 4 - 1cm-4cm (I'm looking at them on the parts shelf)

Not sure how a low rear would make the front rise, it may appear to, but the car will only pivot around the front axle, the front axle load will not alter.

 

[guydewdney]

i sincerely hope thats a typo - 60 degrees is waaaaaaaaay too cold.

60 = barely started
70 = cold
80 = normal
90 = fine
100 = hot
110 = a problem
120 = bang

the thermostat control comes on at 9x degrees (cant remember exactly) - mine has a four stage control - for arguments sake - fan #1 slow at 92, fan #2 slow at 94, fan #1 fast at 96, both fast at 98 (i stand to be corrected on the actual temps, but its around this)

 

[tarmacsurfer]

OK everyone lets all calm down...

My car sits low at the back due to being a Sportline suspended model. The problem at the front is due to Standard springs which are too long and of the wrong stiffness (too soft!)

Regarding temp I will change the thermostat when I drain the coolant next.

Cheers all :wink:

 

[talbir]

>>"No, 90deg is too hot, something wrong with your car, (too close to unpressurized boiling point), normal running temp is around 80 deg, (the gauge pointer should sit just below horizontal) "

Rubbish, absolute rubbish. Operating temps vary from car to car. 80 deg is fine, 90 deg is where the gauge should be. And this applies to the W124 300 engine. On an E500, in warm ambient temps, anything upto 105 degC is NOT a problem, as the M119 runs hot. Different engines have different themostats too. Nothing wrong with my cars, but if your temp needle is sitting below horizontal, you have a real problem sitting round the corner. Any MB technician will tell you the same. They don't come much better than Andy Gayle and he will tell you no different - less than 80 deg C IS a problem !!!

>>"As for cutting springs, well I've heard a few in my time....apart from having the wrong end profile this can only be a bad idea, I would strongly recommend dealer springs, you will not have to worry about correct height, how could you be accurate enough, sure it will be stiffer (less coils to twist). leaving aside physics and mechanical engineering this is just plain daft, how many owners would remove their springs, stick them in the vice and start hacksawing chunks off, maybe they should soften them first..and then re-temper them. "

Why is cutting springs a bad idea - explain.

>>"Packers are available from 1 to 4 - 1cm-4cm (I'm looking at them on the parts shelf) "

What parts shelf you looking at - not MB because MB DO NOT sell rubber pads which are 4cm thick. NEVER EVER for the W124! And the nibs do NOT refer to number of cm's thickness. 1 nib = 5mm, 2nib = 13mm, 3 nib = 19.5mm. Sorry, but you need to get your facts right. 4cm rubber spring spacers - are we talking about MB W124's or Porsche Cayenne's ?????

>>"Not sure how a low rear would make the front rise, it may appear to, but the car will only pivot around the front axle, the front axle load will not alter."

Ever heard of Xenon headlamps ? Well, they work with a self-levelling system, which has a control unit on both front AND rear anti-roll bars. When the car squats from the rear, the front IS raised, hence the self-levelling system for the Xenon headlamps relies on input from both the rear roll bar to lower the headlamp beam when the rear sits low.


Talbir

 

[tom7035]

Butchering road springs with a hacksaw? A definite no-no!! Apart from anything else it would not seat correctly, inviting a fracture and possibly horrendous consequences. Also an MOT failure.

 

[talbir]

Butchering road springs with a hacksaw? A definite no-no!! Apart from anything else it would not seat correctly, inviting a fracture and possibly horrendous consequences. Also an MOT failure.

INCORRECT.

Firstly, the spring only has a contoured coil at the base, to sit in the metal seat correctly. The top of the spring has no contoured coil - you can cut it from the top section wherever you like - the only thing you change is the length of the spring. Cut a coil off the spring and it will sit back exactly as it was, since NOTHING except the spring's length has been changed.

Secondly, cutting one or half-a-coil off has no impact on the rest of the coils. So how a fracture can occur to the remaining coils is an interesting suggestion.

Finally, an MOT failure can only occur if spring is cracked. As per above, cutting a coil length of the spring will NOT cause the spring to crack elsewhere. The most common fracture point for a spring is at the base, where it sits in the metal housing. Since springs are always cut from the top, spring fracture has no relation to length reduction from shortening at the top !

Talbir

 

[tom7035]

Fair enough talbir, but I reserve judgement as I have yet to come across a spring profiled at only one end, but admittedly I am new to MB marque. Any road spring is designed to bear weight around its entire circumference at both ends I think you will agree, so I assume the bearing cup at the top is matched to the spiral of the spring itself.
I must have been unfortunate in that the only two broken springs I have suffered during my lifetime both broke at the top contrary to what you suggest. I tried a 'flannel' with the first, an old Brabham Viva, removed the broken piece and threw it away (now like a cut spring), looked fine, broken end tucked away deep in the spring cup - result, MOT failure. Tester sharper eyed than I thought!
The next was a Mondeo, again broken at the top but replaced it this time before MOT!
I'm never too humble to learn incidentally, but would still not simply cut the springs to make the car sit as I wanted it to.
Cheers, Tom.

 

[mlc]

Talbir. Never have I read a posting so full of incorrect advise! And then you claim that all this knowledge is due to your expertise in Physics.

Wrong!!!

Fact - The concentration of anti freeze is unlikely to have any effect on running temperature. Too much is a waste, too little and the system rusts and may freeze on a cold night.

Fact - Old radiators leak and get clogged up with debris, rust etc. both of which cause overheating. The chances of an old radiator causing excess cooling is zero.

Fact - Running temperature is related to driving conditions and especially air temperature. The AA deals with lots of overheating cars (even MB's) on hot summers days - and very few on cold February days like today.

Fact - The "Stiffness" of a spring is a function of its thickness, composition, hardness etc. and absolutley nothing to do with its length. This is called elastic deformation - just ask any half wit A level Physics student and they will explain it to you. What you are confusing this with is travel - if you cut a lump off a spring it will compress by less distance for a given load, but that doesnt make it stiffer. The idea that you think that just cutting a bit of spring off in the average DIY garage is frightening - I hope you dont drive the same roads as me.

Final Fact - In 30 years of driving, mainly working in road transport, the only occassions that I have witnessed cold running has been with either a thermostat jammed open or a cooling fan running all the time. I have however seen far more cases where the temperature sensor or gauge has been inaccurate.

Please dont give "advise" thats so wrong - somebody might believe you.

Mark.