Thermostatic oil plunger end-plug removal...?

[Jascha]

I was wondering if you good Pelicans can share the approach you have taken to remove the end-plug (slotted cap) to gain access to (test / replace) the thermostatic plunger -without removing the entire external oil valve housing?

I was thinking of simply clamping metal plate (or a six-sided 50 pence coin) with Wise Grip or if need be first heat cycle with the blow torch to be followed by applying standard plumbers’ pipe wrench to the end-plug (soft aluminum is a concern).

Thanks.

Jascha

[Mo_Gearhead]

Jascha,
Year of car and engine size please?

I am confused by your descriptions? First it seems you are wanting to remove the bypass plug (round plug with a slot like a screwdriver?)

Then you describe removing it with a pipe wrench (raised head?)???

Can you photograph the thing and post?

[Jascha]

I wanted to remove and replace the thermostatic plunger (# 4) and rebuild the pressure relief plunger (# 6 …# 9) while the valve housing (#5) remains attached to the oil lines….

Undoing the slotted end-plugs (#1 and #9) proved to be more difficult than expected… I just finished removing the valve housing assembly and still had some difficulty getting the end plugs off (#1 and # 9) off (they were nearly seized!)

I did find a wedge-end ½” driver socket in my tool box that I force-fitted inside the slot and used a portable ‘impact wrench’ to drive # 9. out .

I’ll be sure to post pictures when I get done driving the main offender (#1)…

[safe]

Forget about rebuilding, #6 is expensive and together with the other components its better to buy a new thermostat.
Part #6 has a rubber seal so the blow torch is not a good idea.

You will make some damage with a pipe wrench, but not more than what you will do to the slot if you try that.

[Formerly Steve Wilkinson]

I used a large industrial washer, 2.5 inches in diameter. Had to grind it down slightly where it fits into the slot, but its curved rim fits into the semicircular slot nicely.

[Early_S_Man]

Jascha,

One of the many deficiencies in the Bentley manual is a missing reference to the special tool to remove those plugs, along with citing an opening temperature for the thermostat of 113°F!

Unfortunately, those aluminum plugs are cut with a semi-circular profile slot, and the tool to remove them must be fabricated ... starting with a special tool called a drag-link bit. You need to find one in 3/4" drive that is both thicker and wider than the plug groove, then grind it down very carefully to fit precisely. Grady posted some very nice pics in the following thread:

Thermostat Valve Opening Test....

[Jascha]

I tried my luck using every tool (and weapon) in my armamentarium to remove the end-plugs while confined to the wheel well. I even tried turning the slotted cap (naively!) clamping a 50 pence coin using Wise-Grip –let's hope QE will forgive me (no damage done to the embossed Royal image and crown) but I did dig deeper into the slotted end-plugs...

I discovered the hard way that these end-plugs are impossible to dislodge without the removing the valve-housing assembly. I was gratified being able to remove it with little effort (PB Blaster was of much help). I clamped the valve housing in a wise and used a potable (14.4 Volt) impact wrench (~ 66 ft-lb) and wedged driver socket (Snap-On type) which made it possible (after some effort / excavation) to remove both end plugs. I tried using a standard impact driver but could not get the end-cap to budge.


BTW, the old thermostatic plunger had an imprint "83 deg-C" (valve opening temperature)







In short, spent ~ $50 on Pelican Parts (thermostatic plunger, two springs, two sealing rings) and better part of the morning and feel it was worth the effort...


Thanks for posting all of the suggestions and encouragements...!