New 108 problem! Radiator overheating! - PeachParts Mercedes-Benz Forum

Californian SE · #1 03-06-2009, 10:15 PM

Just when you think you're getting ontop of the problems, more appear.

I was working on the 108 this morning, and had it running for a good 15 minutes - just in neutral. It got really hot (temp wasnt far off 250) and water/radiator fluid starts spraying out from the bottom of the engine - i realise its overheating so I released pressure from the radiator - hence now there is no fluid in the top of it. Its only a 71 280SE so it doesnt have the fan infront of it - and Im not really sure how it works.

Is there a leak from the engine somewhere if it sprayed out the base? I cant see where it was from and I cant drive it on my ramps cause theres nothing in the radiator! What should I do?? I was going to go for a drive in two days - but I dont think thats going to happen any more

Please help me guys - thanks in advance.

Cheers,
Luke

Mike D · #2 03-06-2009, 10:22 PM

Check the water pump. Borrow a pressure tester from Autozoo or another parts house. Fill with water first, of course.

Californian SE · #3 03-06-2009, 10:24 PM

Showing just how little I know about the radiator system - where is the water pump

So the radiator just fills with water??

Mike D · #4 03-06-2009, 10:41 PM

The water pump is behind (on the front of the engine) the fan. It goes; fan, pulley (the round thingie the belts go around), water pump and the engine itself. When they leak it's usually out a "weep" hole on the body of the pump itself. It can be tough to spot without a pressure tester. The weep hole is designed so that if the seal fails, the water exits BEFORE it ruins the bearing and locks the pump solid.

Use water for diagnostic purposes only. After the leak is fixed then refill with the 50/50 coolant-water mix.

Californian SE · #5 03-06-2009, 11:02 PM

Ok, water pump located haha. Filled radiator with water- ran car for 3 minutes or so - but temp was creeping and creeping. got the the notch between 250 and 175 and i turned it off. No leaking or anything - I dont have a pressure tester so do i need to get one - or does is this check enough to ensure that theres no leak???

Mike D · #6 03-07-2009, 07:33 AM

If the radiator boiled over and was dry then you need to "burp" the system when you refill it.

Fill the radiator, leave the pressure cap off, start the car, loosen the heater supply valve hose and wait until water is running freely from the hose. The heater supply hose is the molded hose leading from the cylinder head to the divertor valve (the brass block on the firewall with three heater hoses connected, the supply is the largest hose). Tighten the hose, top off the coolant and replace the cap.

Have you changed the thermostat? Check for corrosion build up in the thermostat housing and in the bypass housing directly below the thermo housing.

Supposedly you can also get a "complete" fill by parking the car on a steep incline, nose up. Open the heat controls, fill the radiator, leave the cap off, wait an hour or so and top it off. I've never had any luck doing it this way but other people have and it's a lot neater than undoing the hose and spilling coolant in the engine compartment.

mbgingerbread · #7 03-07-2009, 08:50 AM

Californian SE;
Your coolant sytem is a closed system except for the radiator cap which is deigned to relieve thru the hose leading from the radiator to either a tank or the ground. The water pump is described above.
You must ensure that your system is full to check your problem-this includes the heater controls. Your inexpensive fixes are to attempt the pressure test above. Then you can replace your rad cap and after that the thermostat. There are a number of pipes/hoses in the system which are hard to find/see so be extra careful looking for signs of leakage. Just the other day I was working on the right side of the engine and noticed that the pipe running from the radiator to the heater core was leaking-just a small leak-wet spot/a little green. My car has been running ever so warm so I will replace this pipe shortly. If the thermostat is stuck closed then the coolant is not able to circulate thru the motor. If you replace the thermostat you will need to loosen the injector lines in order to allow access to the thermostat bolts and to aid in the removal of it. The two slot head bolts are tricky to get out. Remember that you are removing bolts which thread into aluminum-it's easy to twist them off so go slow. I used my trusted impact wrench (hand-held-about 20.00 at Sears or similar) and tapped on the bolts easy-first to tighten ( helps to break the seal ) and then loosen. The last thing you want is to drill an iron bolt out of an aluminum housing. Be sure to renew the gasket and check the thermostat in a water bath to make sure that it will open before you install it. If you do go this route you will have to make absolutely sure your system is purged of air which may require some finesse-check other posts on the site.

Californian SE · #8 03-07-2009, 09:38 PM

Ok thanks a heap for your help guys. At this stage Im only slightly worried about the temp, but its only when its idling, plus the car is getting a full mechanical service in about a month so Ill get it checked out then, I dont think I want to risk it myself. Ill give the car a "burp" as you suggested Mike - which will make sure its full.

With the water in the radiator Ive had a very good look for leaks, and cant see anything though I did hear a treacle sort of noise, possibly just my ears seeing as it was so quiet ~ and there was no water on the floor or anything.

Thanks again for your help guys.

Mike D · #9 03-08-2009, 10:20 AM

Quote:

Originally Posted by Californian SE

With the water in the radiator Ive had a very good look for leaks, and cant see anything though I did hear a treacle sort of noise, possibly just my ears seeing as it was so quiet ~ and there was no water on the floor or anything.

"Treacle"? Your car sounds like a thick syrup?

If you mean "trickle" then you probably just need to burp the baby. Air in the system will cause a "gurgling" sound after the engine is turned off.

mbgingerbread · #10 03-08-2009, 08:19 PM

Californian Se
Just a clarification-the pipes and hoses from the heater core run to the right side of the block and to the air intake assembly. Also, I meant to say impact driver rather than wrench. I have had great success with torque-one of the do it yourself mechanic's best friends when coupled with some impact however slight or heavy.
I would suggest that you purchase yourself a decent How To book on your car. You might enjoy finding that water pump in there!!!