Engine Overheating

Hi...

It is the first time for me to be with you gentlmen and I hope
to be nice with you.

I have Merceds-Benz 560SEL 1991 and I am complaining about
engine overheating only at high speed during hot weather,it reaches almost
max range with AC on or off. During night or driving in the city,I have no
problem.

I replaced radiator, 65*C thermostat,checked engine fan clutch, checked
water reservior cap and all found good.
Electric fans have no problems. They are working ok at different speed.
Engine temp. rises as I speed up. The more I speed, The more temp I see.

What would be the cause of my problem?

Hi Abdullah welcome to the forum. It is nice to have you join us and I hope you will like it here

Perhaps you have air trapped in the system?

Welcome to the Forum Abdullah !

Great recommendation Jeffie !

Also, I think I'd be looking at replacing the Water Pump.

Second, is that 65°C stat, original Manufacturers temperature, and is it a Merceds stat?

Next, I'd look at the Radiator, might be a bit clogged up after all these years ! When's the last time you had the Cooling System cleaned?

Then, but not too common, make sure your Hoses are "fresh", I've seen Upper Hoses collapse and shut the flow off. The wire inlaid type keep this from happening. Usually happens on older vehicles, ones without the Reservior, but, it's still possible.

And, when you check the level of Coolant when the engine is "COLD", is the Radiator completly full ?

Other than the above, tight belts and no obstructions to Air Flow.

Have a good Day !
S.W.

PS: Nice Car !

Post edited by: SWHouston, at: 2008/08/22 15:59

1.Regarding the thermostat: it is original german made.

2.Radiator is new BEHR type.

3.Area between AC radiator and engine radiator is cleaned

before installing the new radiator which means there is no obstructions.

4.When adding anti-freeze & coolant to the new radiator, radiator was

full because I got rid of air trapped throughout the water reservoir hose

when disconnected.

SWHouston reminded me about the upper hose. It looks very week and
one time when engine was cold, I found it collapsed. Do you think this
hose will collapse when engine become very hot and the hose is located
on the discharge line of the water pump.

Abdullah,

UMM, sounds like you got most of the bases covered !

On the upper hose, no, it won't collapse when it becomes hot, it does it when it cools down, and there's a vacuum created in the Engine block.
If any of your hoses are really "soft" like that, you should change them out.

BUT, if your recovery system is working well, that shouldn't happen. I'd certainly look into replacing any hose that is cracked or weak too.

Let's just check again here....

The Radiator Cap you're using with the Recovery system, should have a plate valve on the bottom, which is loose, floppy, when you look at it, right?

The small hose goes from the Radiator Overflow tube, to the BOTTOM, of the recovery Tank, and that Tank is at least half full, hot or cold, right?

Have you checked your Timing, that year should have been Electronic Ign, but if there's any Vacuum Hoses related to the Distributor...no cracks and tight on the fittings, and timing is correct, right?

Have you had your Coolant checked with a "Sniffer" ? That will tell you if you have a High Compression leak into the Water Jacket. Most Radiator Shops or Dealers will have this little tool, and "may" test it free for you.
Wouldn't hurt of you personally saw the reading go into the "Red or Green", just so you'd know it was, or was not bad.

Ok, just as a precaution, you DO know NOT to take that Cap off the Readiator, when the Engine is Hot, right! (just checking ok)
A cool down of about an Hour, should let you in there safely, but "ease" it open anyway !

I'm not sure if that year/model was Fuel Injected or Carburator, but it's possible it's going lean on the Fuel Mixture at higher speeds, which could also be caused by a leaky Carb Gasket, or other Vacuum lines around the Manafold. Most good shops have a "Fuel Mixture Tester, and can check the Mixture at 2000 RPM and higher.

Gees that's a long shot, but, I'm really digging deep here !!

How about those things ?

Have a good Day !
S.W.

S.W.


The car is Fuel Injected,right.

Coolant just perfect I have no dought about it, water reservoir cap is ok too.

I checked both radiator hoses and got this : They are really week and old
beside the lower hose has no spring insid to avoid collapsing.
What I got from this, when engine runs at high speed water pump also sucks too much water from the radiator which in turn makes the lower hose to collpse and not to give the engine enough circulation of the coolant.
This is maybe my problem.

Today, I going to change both hoses and let you know for any news.

Have a nice day!

Abdullah,

GREAT !!!, and YES, if the bottom hose is weak, it well may be the problem, and this can happen when the Engine is hot or cold, and can be Engine Speed related !

However, when you replace the Hoses, try to get the ones with the Wire totally enclosed (vulcanized) within the inter and outer layers of the Hose. They are much better for lasting a longer time.

The ones with the Coiled Wire just pushed inside the hose and exposed, are quite prone to deteriorate after a time. SO, a little more expense now, will save you from more problems later.

Also, I urge you to replace the Heater Hoses now, it is quite likely that they are the same age (or older) than are the Main Hoses. You are going to have to drain the system to replace the Upper and Lower Hoses, and this is a very good time to continue the job, and get all of them in good shape !

We are looking forward to hearing of your progress !

Have a good Day !
S.W.

Caution to the Inexperienced Repairman:
Frequently Heater Hoses can include routing to Flow Valves and can be installed in several sections. IF you disconnect all of the hoses at the same time, frequently errors can be made in installing the new Hose causeing improper routing.
I recommend that you replace each section with new hose, in sequence.
In other words, take one out, replace it, then move to the next section.

Post edited by: SWHouston, at: 2008/08/24 05:00

Yes great job because of all members in the DIY and specially YOU!!!

You asked me about the heater hosess, I removed them because I needed
good AC at noon time as you maybe know We have a very hot summer
in my countery in Saudi Arabia.

I changed both hoses with origenal ones. I could not find the spring which goes inside the lower one , so I brought one stainless 1/8" stick and by using the vice grip, I twissted it around 1" metel pipe for 10" long and inserted it.

Put good quality Anti-freeze and Coolant 50/50, hit the road for 220km/hr
at noon when weather temp at max. I was surprised by temp of 85 to 88/90
with AC on. When I slow down to 140km, temp goes back to 80 to 85

I have a question about the Temp. Gauge. It is divided from 40 to 80 to 120 then red line comes just after it.

My question about the line in between 80 and the line just before the rid " dangar zoon" Actually there are two lines between 80 and rid zoon.What I ment here is the first line just after 80.

Thank you all again and I will be back soon.

last week in north carolina usa. i had a gas tanker with cummins desiel do this same thing. it ended up beening the water pump at high speed bearings were getting hot and siezing up causing belt to slip. empeller baldes were rusted off only had one or two blades left.are temp that day was 105f humidity 98%.no wind or breeze at all.truck was full 3800 gallons of gas in direct sun light on inter state highway in middle of no were changing pump and belts.

hobbist,

WHEW !!, not a position I'd want to be in for sure, hope you baby'ed it along, and got somewhere cooler to fix that thing !

By the way...
Have you seen where I/we are going to re-do the Topics, in Site Feedback.
Sure would like your input on that, where i could do it once, and be done with it.
Just post your recommendations there. Looking forward to those, if any?

abdullah,

Thanks, if that "specially YOU' was directed to me !
I got to give you a "atta boy" too, I know you been doing this with a English Software Translator and probably some knowledge of English, which is NOT an easy language to speak or read. GOOD JOB !

Now, back to your Car....

Really a GREAT substitution/fix, using that Stainless Rod ! But, i hope that coil came out bigger than the one inch you said ! Those hoses are almost two inches inside, and one inch even with a little expansion from the coil unwinding, sounds a little small.

I know parts are probably nearly impossible to get over there in SA now, but I sure wish you had been able to put new hoses on it.
More Auto Parts Stores, less Troops is the way i'd have it!

Now about your temperature gauge....
It may be the older "Bulb and tube" type, or, a newer "Electronic/Electrical Type, with just a single Wire on the Sensor.

Either way, those things are not very accurate, BUT usually are consistent. So if you learn just what yours is telling you, it will be fairly dependable.

Now keep in mind...(and i got to do this in F°, you can change it to C° )
For every Pound of pressure you put on the Cooling System,
you INCREASE the Boiling Point of the Coolant, 7.5°

SO... IF you have a 15 Pound Radiator Cap on it, then your
Boiling Point is increased 112°, making it a total of 324° (approximately)

You see that you got quite a bit of "room" to deal with there, plus, some expected high temps, since you're dealing with Desert conditions over there.
Now, under those conditions, running a Temp of 250° to 300° about, is not uncommon, and will not hurt your car, given you have good oil and coolant in it, which i feel you do have.

So, if your system is running 90°C or less, you are NOT in any trouble at all !

Now, about your temperature gauge. is it right, and what do the marks mean?

This post is getting too long anyway, so, i'm not going to give you the procedure/How-To for that test here. I'll write a separate Post and put it in the DIY Tips section, then come back and give you a link here, to get to it easily.

So Abdullah, I applaud you for hanging in here and getting this done well. GOOD JOB !!

Have a good Day !
S.W.

PS: I'm just dieing to know what his Translator does with "atta boy" !

first, my car becomes very good. I noticed engine is running smoothly. when I drive the car, acceleration is much more better than before.

The upper hose has ID is 2" but the lower hose has just 1.25". When I twisted the stick around 1' metal pipe it was under tention, then when
spring it expanded little out making an outside diameter more than 1" which
I could not insert without lubricant.

The images below show the difference of ID of lower and upper hoses :






Post edited by: Abdullah, at: 2008/08/29 13:51

Abdullah, perhaps you have to buy the proper sized hose? (I am just guessing here... )

Hi...Jeffie

Actually I tried to put another type of hose which has the same shape and has a bigger ID but when I put it, the engine cranck pully starts eating the hose because I found the space is not enough to accommodate any bigger hose.

This hose when is set proparly, there is a clamp holding it to prevent it from touching the moving belts and the pully.There are only few milimeters between them.


What you see are the original hoses for this car.

Abdullah,
Sorry about the delay here, had family over !

Car running better !, they always seem to when you do something to them

The second picture didn't come in, but, I'm not sure that it's necessary that you send it again.

I'm not understanding this, you seem to have conrrected the problem, and I think that is what you are telling us, that everything is ok now.

About the smaller bottm hose, it is ok as long as the coil fills the Hose, that is good. And if you have it in place, and it is not being rubbed, then i think that everything is ok !

Is that what you are saying ?

Have a good Day !
S.W.

Jeffie wrote:

Abdullah, perhaps you have to buy the proper sized hose? (I am just guessing here... )

My car is running ok without any problems.

The hoses are different is size and still original.

The lower is smaller in ID than the upper due to small space provided.

I wanted it to be cleared that`s all.

Thank you so much.

Post edited by: Abdullah, at: 2008/08/30 13:43

OK then. Who could have guessed. It always seemed to me incompatible sizes (for anything, not only those hoses) cause problems.

You taught me something. Thanks, Abdullah

Good !,
I'm glad that it's running ok!

However, I'd still like to hear that you replaced those older hoses, with the Wire Inlaid type at some point, if you choose.

Have a good Day !
S.W.