Running hot

Tiny
MESANTO
  • MEMBER
  • 1999 VOLKSWAGEN JETTA
  • 144,000 MILES
I have a 1999 volkswagon jetta wolfsburg edition 2.0 runs great last week I replaced the Mass air flow sensor and it runs great except it runs hot due to the water in the little reservoir running out all the time. I filled it up last night and it seems to be losing water somewhere. And why does this car only have a small little area to put water in?
Monday, December 12th, 2011 AT 3:37 AM

15 Replies

Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Because that's the way they designed it.

There are many reasons that it might run warm.
Too lean.
Clogged radiator.
Rust buildup in the water jacket.
Failing water pump.
Obstructed radiator.

Just to name a few.
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Monday, December 12th, 2011 AT 4:25 AM
Tiny
MESANTO
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  • 27 POSTS
Ok thanks where would I start to get the radiator checked myself as far as the in the water jacket? Whats that? When you say to lean what is that refering to? Any help is greatly appreciated
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Monday, December 12th, 2011 AT 5:29 PM
Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
If you cant see or smell where your losing water it may be burning out the exhaust. In that case you have gasket issues with engine or internal cracks.
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Monday, December 12th, 2011 AT 5:41 PM
Tiny
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Too lean means the air-fuel ratio is incorrect-not enough fuel for the mass of air.
The water jacket is the path inside the engine block that the coolant flows through.
You can try and kill 2 birds with one stone by performing a power flush on the cooling system. Remove the thermostat, replace the housing, and use pressurized water through the cooling system. Just make sure you collect the old coolant, since in many places it is a crime to allow it to run into the sewers.

As fixitmr mentioned, do you have any white smoke coming out the exhaust? The best way to locate a leak is to pressure test the cooling system. You should be able to rent or borrow a tester from a parts store.
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Tuesday, December 13th, 2011 AT 1:24 AM
Tiny
MESANTO
  • MEMBER
  • 27 POSTS
Thanks guys well today when I looked at it I put some water in it than I had to take the car on a drive to the dentist. No problems at all the car did not over heat the gauge the other night would go back and forth almost all the way to the right than it would make its ways back to the center where its usually at. But today it stayed right in the middle and when I got back home I checked the fluid in the tank and all the water was still there. I will keep an eye on it and keep my eye on it !
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Tuesday, December 13th, 2011 AT 2:57 AM
Tiny
MESANTO
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I changed the mass air flow sensor last week as well I put in a remanufactured one that I got from auto zone
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Tuesday, December 13th, 2011 AT 3:04 AM
Tiny
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  • MECHANIC
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Let us know if the new MAF sensor fixes the air-fuel ratio problem.
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Tuesday, December 13th, 2011 AT 3:29 AM
Tiny
MESANTO
  • MEMBER
  • 27 POSTS
I am assuming it is cause the car idles much better and does not stall at all anymore. It put a fix on my wallet $115.00 OUCH
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Tuesday, December 13th, 2011 AT 3:59 AM
Tiny
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Much better than replacing injectors, though. Or a fuel pump. Have a Happy Holidays and thanks for keeping us apprised.
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Tuesday, December 13th, 2011 AT 4:34 AM
Tiny
MESANTO
  • MEMBER
  • 27 POSTS
Ok I have to ask cause it just dont look right on my main serpentine belt looks to be off the what ever its called I have attached a picture here hopefully it will help out. Where the belt come around on top there is a round device that I am assuming keeps the belt inline but on part of the belt is on that round device is that normal? Do I need to adjust it? It seems to be ok the car seems to be ok with it the way it is. Here is the picture I took of it this morning hope it helps out
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Wednesday, December 28th, 2011 AT 3:06 PM
Tiny
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The picture didn't make it through. The device on top is probably the tensioner. IS this what it looks like?
Image (Click to make bigger)
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Wednesday, December 28th, 2011 AT 6:40 PM
Tiny
MESANTO
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Yes its the part that is in this picture that is in the middle left center yeah for some reason the pic didnt load correctly
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Wednesday, December 28th, 2011 AT 6:52 PM
Tiny
RIVERMIKERAT
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Ok. Look at the image here again. The arrow labeled "A" points to the tensioner spring housing, while "B" points to the tensioner pulley itself. The belt doesn't go around the spring housing, just under the pulley. To the right of the tensioner pulley is the alternator/generator and under that is the AC compressor.
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Wednesday, December 28th, 2011 AT 7:20 PM
Tiny
MESANTO
  • MEMBER
  • 27 POSTS
ITS B
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Wednesday, December 28th, 2011 AT 9:59 PM
Tiny
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That's the tensioner pulley. The belt should be pretty much centered on it. A few millimeters one way or the other is fine.
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Wednesday, December 28th, 2011 AT 11:46 PM

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