T350 Coolant change/top-up (w/ expansion tank)
T350 Coolant change/top-up (w/ expansion tank)
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stuart.penney

Original Poster:

3 posts

Hi all,

Never really had much dealing with a coolant system before so any guidance would be much appreciated.

Car seemed to be running a little hot, particularly while stationary and both fans are running correctly so decided to investigate.

The expansion tank was bone dry and the swirl pot was a bit low so topped up with (the correct) water. Not entirely sure of the coolant in there currently so will come back for a complete flush and change later on, and probably take the opportunity to fit some lovely silicone hoses too!

Topped up at the swirl pot to level with the upper most hose, but since then it seems to be depleting more frequently. Do I need to bleed the system? How? Where? Etc etc.

Also, to be a pain, I’m a very visual person! So any images people have of previous work and locations of critical components would be great!

Thanks in advance. Will also be at the Silverstone Classic end of the month so if anyone there is happy to talk me through it in person lunch is on me!

UPDATE: definitely a leak, seems to be coming from the front of the block, too hot to identify the exact source. I have pre-ordered new hoses, but would still absolutely welcome some guidance

zeppo

252 posts

206 months

Saturday
quotequote all
Do you find some water on the Metal Plate below the Engine on the Right Side?
If yes, it could be a leaking waterpump.

Granturadriver

664 posts

277 months

In my experience, the amount of water regulates itself. In some cars, the swirl pot is probably filled to the top or the expansion tank to the lower third, but in my own car it is different, as the swirl pot is only a good two thirds full.

If it contains too much coolant, the car drains it via the cap.

To bleed the air, the circuit should of course be filled, ideally with the front of the vehicle jacked up or at least raised. The last time I left the car running with the cap on the expansion tank open, air bubbles out of the system.

If the system is also loosing water from time to time, then there must be a leak.

It also makes sense to check whether the two fans are blowing in the right direction. In my case, there was a fault after replacing the plug connections, the second fan was blowing in the wrong direction, which also led to problems.

stuart.penney

Original Poster:

3 posts

Thanks,

Yes, my first thing I checked was the fans but both seem to be operating correctly.

I suspect, despite the leak, having now done some further reading simply topping up the water was not going to give me the best interim results. For example, running the car with the heater on while topping up.

So far as I can tell, I ll fill at the swirl pot (I don t see the need to fill at the expansion tank although it s technically highest point due to where the hose is routed and in my mind it s simply an overflow and not really part of the circulating system).
Run the car with the heater on full, all the while keeping the pot topped up (I ve been using a wooden skewer to measure as I go along but as you say any excess will be expelled naturally without causing any problems)
Shut the car off while warm but not boiling and bleed the radiator, again topping up as I go and repeat a few times.

There would appear to be 2 bleed points (I have the flat rad) on the each of the pipes, so I’ll do both. Due to them been located toward the “back” of the rad I wasn’t going to jack the car up either so as not to make them a low point.

If anyone has a different view, process, advice ?

Edited by stuart.penney on Sunday 3rd August 10:04