With warmer temperatures upon us a little early this year, it is paramount this time of year to ensure your cooling system is up to snuff. There are many ways to do this (installing our aluminum radiator and six-blade fan is our favorite upgrade), but it’s also important that you have a decent indicator of how well your cooling system is functioning at any given time.
All British sports cars tend to run hot, so a good temperature gauge is important. They’re not always perfectly accurate (you can check accuracy with an IR temp gun), but they at least indicate temperature trends.
Originally on Bugeyes, the probe for the mechanical water temperature gauge, which is a long brass tube filled with ether (of all things), was installed in the side of the radiator. While this is an acceptable location for getting a baseline temperature reading, it doesn’t tell the full story of how hot the engine is getting, which typically runs hotter than the radiator under normal operating load. It would also render the temperature gauge useless if the thermostat were to stick closed, cooking the engine while the radiator (and temperature probe mounted inside it) were slow to report a problem.
As a result, when possible, the temperature probe should be relocated to a port on the engine, to more accurately relay the temperature of the coolant inside the engine, allowing for better overheating management.
How do you do that? On original Bugeyes with 948 engines, you cannot, as such a port does not exist in the head. However, if your engine has been switched to a 1098 or 1275 from a later Spridget (or if your 948 has had a 1098 head fitted), there is a handy-dandy port drilled right in front of the foremost spark plug towards the thermostat housing!
In order to relocate the probe here, you need to install an adapter into the head port. This allows the proper spacing for the probe to fit in between the coolant passage and the head casting. We offer the adapter for sale in our catalog; you can find it by clicking here.
This week, we had a Bugeye come into our shop that had a complaint of a non-functional water gauge. It didn’t take long to figure out why. Whomever had done the engine swap on this car to a 1275 moved the temperature probe, but did so without installing the correct adapter. As a result, the probe fouled on the inside of the head, bending the brass bulb and puncturing it, rendering the gauge inoperable. This is an easy fix, but it means changing out the entire combination gauge, as once the bulb or line has been compromised, the gauge is no longer usable.
The real lesson that should be derived from this is that if you are installing something, or tightening a fastener, and you encounter a sudden increase in resistance, STOP! You are one wrench turn away from potential disaster. One broken bolt takes a 30 minute job and turns it into a six-hour nightmare. In this instance, about 4 turns too far on the nut holding the bulb in the head took a five minute relocation and turned it into a 45 minute gauge change that didn’t have to happen.
Of course, should your Bugeye or Spridget’s temperature gauge be compromised, we offer two different styles of combo gauge that are direct replacements for your original! Click the photos below to get yours or click here for our full catalog!