Mazda626 Forums: Overflow Tank Reservoir Issue - Mazda626 Forums

Jump to content

  • (2 Pages) +
  • 1
  • 2
  • You cannot start a new topic
  • You cannot reply to this topic

Overflow Tank Reservoir Issue

#16
User is offline   themazda666 

  • Newbie
  • Pip
  • Group: Members
  • Posts: 8
  • Joined: 30-October 09
  • Car: 2000 626 v6
Is there a difference between "backfluhing" and "flushing" the radiator?
And i've also read a few different ways to flush it. What is the proper procedure?

#17
User is offline   vegas d 

  • Newbie
  • Pip
  • Group: Members
  • Posts: 10
  • Joined: 17-June 10
  • Car: 1999, Mazda 626, V6, Auto

View Postthemazda666, on 18 November 2009 - 02:58 PM, said:

2000 626 V6

been searching for days on the info i need but can't seem to find it. Earlier this year i've had my timing belt, water pump, radiator and gaskets replaced. Recently i noticed the temp gauge was not responding as it normally would and the car would begin to overheat. On one occasion the temp gauge needle went past the half way mark and rose near the "H". On the other occasion it rose just past the mid-way mark. after reading thru a few forums i replaced the thermostat and now what i'm getting is coolant or really hot steam spewing from the overflow tank reservoir out of the overflow rubber tube. and i also noticed that it's leaking at the seams.

What's causing the steam or coolant to spew out.



Hi, I own a 99 626 V6 and have continually had simular issues as this. I'm wondering if you found a solution and if so, what fixed it? I've had the entire cooling system replaced, and I've had to replace the overflow tank 5 times. Each time it does the same thing, around 5 to 8 months old it starts leaking around the seam - spewing steam, losing water and the car overheats. I bought the first replacement tank from a Mazda dealer, and since each one since has failed within 1 year they replace it for free. But it's getting old. If you've found a solution, I'd appreciate it. Thanks.

#18
User is offline   snailman153624 

  • Mazda 626.net
  • Group: Admin
  • Posts: 13,383
  • Joined: 16-February 03
  • Location: WPB, FL
  • Car: N/A
You probably have a blown head gasket, and are getting exhaust gas blowby into the coolant, which overpressurizes the tank.

#19
User is offline   vegas d 

  • Newbie
  • Pip
  • Group: Members
  • Posts: 10
  • Joined: 17-June 10
  • Car: 1999, Mazda 626, V6, Auto

View Postsnailman153624, on 17 June 2010 - 03:53 PM, said:

You probably have a blown head gasket, and are getting exhaust gas blowby into the coolant, which overpressurizes the tank.



Wouldn't the car run badly if I had a blown gasket? Will an engine block and pressure test determine if it has a blown gasket, or do I have to have a compression test? Thanks.

#20
User is offline   audiqv8 

  • Member
  • PipPipPip
  • Group: Members
  • Posts: 232
  • Joined: 19-July 06
  • Location: Chicago, IL
  • Car: 1999 626es 2.5L V6 auto, 1990 Miata 1.6L Manual

View Postthemazda666, on 25 November 2009 - 08:21 PM, said:

View Posthant9925, on 25 November 2009 - 06:33 PM, said:

To find the unit, simply follow the radiator hose that leads from the coolant tank to the engine block. Just beyond the "other" radiator cap, you will see the TSU sitting on the engine block. There's a wire and socket (it's grey in color )that connects the TSU. I think you need a 10 mm or a adjustable wrench to remove it. Fairly easy job. Make sure your engine is cold when you replace it. The coolant has a habit of squirting out when you are removing it. A little dark right now for me to get a photo of it..let me know and I can get one for you if you can't find it. As for the relays, they are located on the drivers side. But since both your fans are working, your relays are fine.


Guessing this little guy here is the TSU. Now if it needs to be replaced how can i tell or should i just replace since my temp gauge is still off.

Next question is about the hoses running from the Res tank. The "L" shaped hose should be the one on top right?


Even though this post is old, I wanted to point out that the radiator caps are reverse. From his picture the cap on the engine side is wrong. Since this problem occured after a timing/waterpump replacement, it appeared that they reverse the caps.

#21
User is offline   snailman153624 

  • Mazda 626.net
  • Group: Admin
  • Posts: 13,383
  • Joined: 16-February 03
  • Location: WPB, FL
  • Car: N/A

View Postaudiqv8, on 20 June 2010 - 08:03 AM, said:

View Postthemazda666, on 25 November 2009 - 08:21 PM, said:

View Posthant9925, on 25 November 2009 - 06:33 PM, said:

To find the unit, simply follow the radiator hose that leads from the coolant tank to the engine block. Just beyond the "other" radiator cap, you will see the TSU sitting on the engine block. There's a wire and socket (it's grey in color )that connects the TSU. I think you need a 10 mm or a adjustable wrench to remove it. Fairly easy job. Make sure your engine is cold when you replace it. The coolant has a habit of squirting out when you are removing it. A little dark right now for me to get a photo of it..let me know and I can get one for you if you can't find it. As for the relays, they are located on the drivers side. But since both your fans are working, your relays are fine.


Guessing this little guy here is the TSU. Now if it needs to be replaced how can i tell or should i just replace since my temp gauge is still off.

Next question is about the hoses running from the Res tank. The "L" shaped hose should be the one on top right?


Even though this post is old, I wanted to point out that the radiator caps are reverse. From his picture the cap on the engine side is wrong. Since this problem occured after a timing/waterpump replacement, it appeared that they reverse the caps.


I didn't look at the picture, but that would definitely do it!

#22
User is offline   Big_Al 

  • Newbie
  • Pip
  • Group: Members
  • Posts: 17
  • Joined: 17-January 09
  • Gender: Male
  • Location: Knoxville, Tn.
  • Car: 1999 mazda 626 6 cyl. auto trans
Does the cap with the spring go on the overflow tank or the engine side? Just too clarify .

#23
User is offline   audiqv8 

  • Member
  • PipPipPip
  • Group: Members
  • Posts: 232
  • Joined: 19-July 06
  • Location: Chicago, IL
  • Car: 1999 626es 2.5L V6 auto, 1990 Miata 1.6L Manual

View PostBig_Al, on 29 June 2010 - 07:24 PM, said:

Does the cap with the spring go on the overflow tank or the engine side? Just too clarify .


The cap with the spring goes on the overflow tank.

Share this topic:


  • (2 Pages) +
  • 1
  • 2
  • You cannot start a new topic
  • You cannot reply to this topic

1 User(s) are reading this topic
0 members, 1 guests, 0 anonymous users