Inlet Manifold Bypass pipe Problem....Help!!

[norman m. macleod]

Hi All,
Greetings again from Down Under......My last post indicated the start-up (at long last....!) of the engine in my Series 1 2+2 restoration. Regrettably the joy did not last too long, as, after about 10 minutes of fast idle, the worm clips at both ends of the by-pass pipe C24581 seemed to fail, with high pressure
steam and coolant issuing forth. Assuming that I had somehow forgotten to tighten these up properly, I let the whole plot cool off overnight and tightened them up next day. Start up again, and the same situation within 8-10 minutes again....Mmmm.....
I should explain that, for various reasons, the set-up up front is a bit of a mixture, and I wonder if this is where the problem lies. The engine is a Series 3 XJ6 4.2, and has a conventional E-Type manifold C24581 bolted onto it, with 3 x correct SU HD8's. It has, however, the Series 2 thermostat housing, and it is to the underside of this that the by-pass pipe attaches (the other end attaches to the top right-hand side of the radiator, which is a new alloy Series 1 type, with new header tank, etc.
The questions I need reassurance on are:-
(1) Is it OK to fit the E-Type manifold directly to the XJ6 Series3 head...?
(2) Should I perhaps have the Series 1 thermostat set-up, which does not seem to have the housing C28212 on the end of the manifold......
(3) Should the (new) otter switch have actuated by the time I have about 90 deg.C on the dash water temp gauge? It did not, but with a jumper across the terminals the cooling fan started up OK. What temp is it supposed to actuate at (the otter switch I mean.....)
I have a gut feeling I've got something wrong with the rad type and thermostat arrangement, but I'm sure the are owners wiser than me out there.....All comments/opinions/input gratefully received.......
(In passing, the entire manifold/carburettors was supplied completely rebuilt by Classic Carburettors in Cirencester, top level work, so I'm sure no problems there.....)
Kind regards,
Norman.

[norman m. macleod]

Correction.......Inlet Manifold should read C24558 not C24581.......
Regards,
Norman.

[PeterCrespin]

(1) Is it OK to fit the E-Type manifold directly to the XJ6 Series3 head...?

Yes

(2) Should I perhaps have the Series 1 thermostat set-up, which does not seem to have the housing C28212 on the end of the manifold......

You could use a total S1 system but sleeve thermostats and right side bypass are old-tech
I used a modern poppet type in the S2 housing on the S1 manifold. I had the bypass running from under the S2 housing direct to an inlet nipple on the water pump intake above bend where the heater return connected to the back of the pump inlet. I blanked off the radiator bypass inlet and almost fully plugged the right side expansion tank hose to the top of the right rad tank. Actually, being a Triumph twin man, you'll understand I used a plug with a hole in the centre for a little flow, made out of an early timing cover oil pressure relief valve dome, that had previously featured the tell-tale plunger sticking through the centre. The net effect was to put all the hot coolant through the whole rad matrix and none of cold 'warm-up' coolant through the rad.

(3) Should the (new) otter switch have actuated by the time I have about 90 deg.C on the dash water temp gauge? It did not, but with a jumper across the terminals the cooling fan started up OK. What temp is it supposed to actuate at (the otter switch I mean.....)

Depends on the switch spec. And how good the fan is. Don''t trust the gauge until calibrated. The top hose to the tank should be cold until about 70C but the external temp may be lower. Then the thermostat begins to open and in a minute or so the hose is too hot to hold. Maybe 5 mins later around 85C the fan kicks in and off again after 3-4 min down to 75. Fast idle is a fair stress test.

I have a gut feeling I've got something wrong with the rad type and thermostat arrangement,

Gut feel is poor second to fact checks and temp/time measurements...

Pete

[norman m. macleod]

Thanks Peter,
Many thanks for your prompt and helpful response..... From your description, I must assume we are referring to a Series 2 water pump being fitted (with the additional spigot on top of the inlet bend......) as the Series 1 pump only has the one spigot to the rear, for the heater connection....?
Best regards,
Norman.

[PeterCrespin]

That's what I did Norman, to have a good fit in the S3 XJ cover (albeit I shortened spindle and pulley to give 1/2" picture frame clearance).

However, the 3.8 pumps have the bypass inlet spigot, albeit the pulley and bottom hose/metal pipe run needs adapting to 3.8 spec, depending on exact rad connection etc. I went for the bigger pump but if a 3.8 fits it would easily be OK functionally with the rest of the system in good nick or 'upgraded'.