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02tom

S14 Operating Temperature Spike at Idle

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Finally getting some time to road test the car upon getting the car operational.  Initially, even before being able to put some miles on it, I had to remove the windshield washer reservoir and pump that was located on the right side above the header as the heat had loosened the pump internals and at idle, was siphoning washer fluid out the right side nozzle.

 

Going forward, I notice that while driving the car in moderate ambient temperatures, the car stays fairly cool - below the half way mark on the factory temp gauge.  While at idle, the temperature spikes to maybe 3/4 of the way up, but not to the red area on the gauge.  No loss of coolant at any time so far, but am concern about what will happen in 90 to 100+ degree weather this summer.  No overflow tank, yet either fwiw.

 

From memory, there's a 71C degree thermostat installed, no fan on the engine itself, and the largest pusher fan possible in front of the Silicon Garage radiator.    The fan does come on at the appropriate time after the car warms up.

 

I've read thru many of the related posts on the subject, but can't find anything similar yet, as most posts are dealing with actual overheating.  Any thoughts?

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Maybe you have some air trapped in the cooling system.  Try parking nose down on a hill and burping the hoses to force coolant into those air pockets, top off the radiator and see if it helps.

 

Mark92131

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(edited)

I agree with looking for trapped air.   l always beed my car with the front jacked up the radiator is the highest point in the cooling system.  If you are not careful you can trap air in the head.  Did you keep the small hose that comes off the head?  On the e30 M3 that hose goes to an overflow tank,; on my 2002 I ran the hose into the radiator inlet.  Are you using the S14 thermostat?  I ran my S14 with a 320i radiator for many years in Miami as my daily driver, and did not have overheating problems.  One advantage of the 320i radiator is that it is slightly wider than the 2002 radiator, and after trimming the radiator support it had increased airflow compared to the 2002 radiator.  I'm not sure that would be enough to explain the difference between what I saw vs what you are seeing, but it is an option to consider going forward.

Edited by Ian

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My forward- going statement  would be to check lower hose temps.

 

When you find them high, suspect radiator capacity

and if that is good, fan capability.

 

If the lower hose is cool (120f or lower) trapped air or a sticky

t- stat are forward to your continued cooling future.

A new t-stat may very well be sticky.  And 71 seems too cool.

 

t

living about 7 years behind the times

 

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I think you should be running a hotter tstat too. If your thermostat is not keeping a stable enough temperature under more extreme conditions or even possibly at idle then your cooling system doesn’t have enough capacity. 

 

You may very well have an obstruction because it sounds like your hardware is sufficient?

 

What about the water pump? Is that in good enough condition?

 

Last I checked the cooling system is least effective at idle so if something is causing it to be running under capacity it would manifest itself there or at very high loads...

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I'll have to look again at the small hose that comes off the head, or have help identifying where it should be.  I think that passage may be blocked at this point?

 

The radiator from Silicon Garage (Curt Ingraham) is described as: 
3 Row Copper core O.E. Brass tanks Turbo width
and should be better than a stock 320i radiator I would have thought.  I just was trying to confirm that the spikes in temperature were unusual, and am looking at how to improve on this.  I have a moderate incline on my driveway that I will try to raise the front of the car and bleed any air off.  First, I'm going to get infrared heat temp gun to help in the effort.  Should have already bought one I guess.


The 70C degree thermostat was what came recommended in the conversion book - which may need updating as it was written in ~1995 I think.  I know there's more than a few notes written in the margins at this point.

 

I had no reason to suspect the water pump when I installed it, but you never know I guess.

 

 

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How quickly does the spike happen? Could it be an issue with the gauge?

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4 hours ago, 02tom said:

I'll have to look again at the small hose that comes off the head, or have help identifying where it should be.  I think that passage may be blocked at this point?

 

+1.  Remember air rises, water goes down.  It should have a constant rise to the routing from the head to get rid of the air..  The head is not self venting and will not get rid of the air without a good vent.

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(edited)

you should be using a stock S14 t-stat.  it also has a port for the elec fan switch(use the stock s14 fan switch.)

 

what electric fan are you using?  that is critical.  i have an oversized three row silicon garage turbo rad.  initially my car was doing same thing...getting a little warm at idle or in traffic.  i was running a 12in BeCool fan.  swapped to 16in SPAL.  problem gone.  fan comes on a tick over half on the temp guage, goes off a tick below half.  temp never goes higher than that except on a hot day doing full tilt boogie on the race track.

 

fans

2014-01-11_12-30-01_141-1.jpg

 

fan

DSCN6038.jpg

 

small cooling hose loop visible

DSCN5557.jpg

 

t-stat

DSCN4915.jpg

 

Edited by mlytle

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Still have a coolant line off the head to the cobbled up T over the water pump. 74381f5f33d8da181b87aa6a4c65203b.jpg

Sent from my SM-N960U using Tapatalk

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The fan is a Maradyne - originally bought a 14", but it would not fit, so I'm guessing I have a 12" in there.  This may be the problem...   I've still got the 14" box with the fan in it set back for another project, and just found both invoices, so the one in the car is a 12" fan.  Maybe the SPAL fits better, but I have the added complication of needing a thin fan motor to make room for the AC condenser which may have been part of the problem with the lack of space.

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spal is very thin.  notice i have the oil cooler in front of it.  tight, but it fits.

 

12in is way too small a fan.

 

A/C?  bah! extra weight and drag.  open the windows and go faster....:-)

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