SteveWallace
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| posted on 10/2/13 at 05:59 PM |
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Temperature sender drill and tap??
I want to add a dashboard water temperature gauge to my BMW Viento build. This needs to be on the cylinder head side of the thermostat (I have a
separate sensor for the radiator fan). The picture below is an attempt at showing my options and shows the near side of the cylinder head near the
front (apologies for the quality)
A = A dual BMW temperature sender in the one solid state housing. One sender is for the original BMW dashboard gauge, the other for the ECU. I
cannot remove this and swap it for the sender for the new gauge as the ECU needs a signal from here and the resistance range of the BMW sender will
not match that expected by my new gauge
B = Not easy to see, but this is just a blank part of the cylinder head casting. In a one year older engine, BMW used two separate temperature
senders instead of what they now use in A. In that case A was just for the ECU and B was at tapped hole for the dashboard gauge sender. Had my
engine been a year older, I would have just swapped senders at B.
C = The cooling water outlet that goes to the Throttle Body. This is a threaded connector into the cylinder head with a pipe fitting on the other end
for the hose. I guess that I could put a T into the hose and put my sender here, except that the ID of the hose is only about 12mm and I cannot find
a suitable T to take a threaded sender. All of the ones that I have found are for larger diameter radiator hose.
There is another option on the other side of the cylinder head where there is a coolant drain plug which I could just replace with the sender.
I'm reluctant to use this though as its close to the exhaust manifold and towards the back of the cylinder head, so not really in the right
place
The 'obvious' solution is to drill and tap a new hole at B, so my question is really how hard is it to do this and what is the risk of
trashing the cylinder head in the process (obviously I will remove everything in the way so that I can get clear access). Alternatively, if anyone
knows where I can get a suitable T for use with the hose then I will go for that as the lower risk option.
Views and advice appreciated...
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theprisioner
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| posted on 10/2/13 at 06:27 PM |
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I assume port C is a heater connection. If so then the water in it is always at enginge coolant temperature even if the thermostat is closed (Assuming
you do not have a heater water valve).
If this is all true you have another option. Put an in line sensor tube in line with the heater connection. These are available at 32mm not sure about
smaller sizes but it is easy to make on the lathe.
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rusty nuts
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| posted on 10/2/13 at 06:51 PM |
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As previous answer . I used a home made connector with a threaded hole for the sensor in the heater hose when I converted my Xflow to injection
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SteveWallace
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| posted on 10/2/13 at 09:31 PM |
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I've only managed to find 32mm ones, so I would need to make one up on a lathe. Its probably a better option that drilling and tapping the
cylinder head because one mistake and its toast. I assume that I would just get a rectangular cross section aluminium bar, turn the ends, drill a
hole through the middle and then tap a hole in from the side to take the sensor?
All I need now is a lathe!
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rusty nuts
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| posted on 10/2/13 at 09:37 PM |
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I used a piece of ally bar about 50mm in diameter , turned each end out to suit the hose size, drilled though , then made a small flat on the side ,
drilled and tapped to suit the sensor, opened the tapped hole out in the center of the bar then tapered out where it was turned down to blend
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