Ian Foster
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Posts posted by Ian Foster
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11 hours ago, Kevin Atkins said:
The car runs just fine though, so very happy.
That's excellent news.
Hopefully you can enjoy the rest of the season.
Ian
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Kevin
Remember that you will have to re-torque the head after about 500 miles.
Ian
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Kevin
Looks as though the issue has been identified with respect to HG clamping.
Head off and gasket change is probably the only logical step at this stage. IIRC stud threads should be lightly oiled prior to installing nuts and torqueing up. Best to torque-up in stages.
From your original post I'm not sure the head has been off before in your ownership, so at least you'll have the change for a good de-coke and polish up.
At least you will have some advice to follow on the cooling system refill.
Please keep us posted re progress and results.
Ian
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Interesting, not seen that before. My factory WSM covers Mk1, Mk2 & Mk3 and yes 60-80lbft for the MK3 on page 0.116 Fourth Issue. Just not looked at that page before, as I have a Mk2.
Strange that is significantly higher than the Mk2 (+15% on the upper figure) and a with a much greater range as well.
Hopefully this information will be useful for Kevin.
Ian
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Hi Kevin
You haven't stated whether your car is a Mk1, 2 or 3. From the use of a 13lb radiator cap I had assumed a Mk3.
If that is the case, the cylinder head uses the bigger 7/16" studs and should be torqued to 65-70lbft (the Mk1 has 3/8" studs as is torqued to 42-46 lbft)
You said you had re-torqued to 44lbft.......
Ian
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2 hours ago, Kevin Atkins said:
Paddocks mention a radiator bleed hose too but I'm not sure where / what that is.
Hi Kevin
I suspect that is the additional hose from the thermostat housing to the radiator neck. The GT6 is the only car in the range to have this, so I suspect Triumph were struggling from the get-go!
Noted what you report re #5 cylinder reading, but please exhaust other possibilities before pulling the head off. Was your compression test carried out dry or wet and did you have the throttle fully open?
I still suspect a dodgy radiator cap and hope you might be able to try another known cap before going further.
Gully, I note what the WSM says, but in my experience it's not that easy and even modern cars have a more comprehensive bleed procedure.
Ian
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Hi Kevin
The GT6 cooling system can be a bit of a challenge. It's marginal at best.
I am surprised that there is pressure in the system after a few days, as there should be negative pressure as the engine cools which draws expelled coolant from the overflow bottle.
My immediate guess would be that there is an issue with the radiator cap. Are you using a 7lb or 13lb cap? (not sure why it changed from mk1/2 to mk3). The radiator cap is sealed at two levels. The lower seal sits in the inner shelf and is responsible for regulating the pressure via the spring, allowing excess coolant to be diverted via the space between the lower and upper seal to the overflow bottle. The top seal in the cap closes off the whole system. There is a small brass valve on the underside of the lower seal which opens under negative pressure. For the return flow from the overflow bottle to the radiator to work, there needs to be a good seal around the top of the radiator neck (this was an issue for me). If you put some fine wet & dry on a flat block and tickle to top surface of the radiator neck, you will see whether you have any high/low points.
Secondly, are you sure you have fully bled the system. It's not easy to do and I have developed my own routine, which essentially uses a bleed bucket in the radiator neck and also a tapping in the thermostat housing, which is the highest point in the system. (I experimented with a header tank at one point which is why I have the tapping).
The heater control needs to be set to hot. I fill really slowly without the engine running and with the thermostat tapping open (small elbow, short pipe and small funnel attached), giving the two top hoses and the bottom hose a good squeeze every now and then. I then fit my bleed bucket (actually just a juice bottle) add a bit more coolant to create a small head and then start the engine and wait for air to start bleeding out of the radiator and thermostat. I add more coolant as required and massage the hoses. It's surprising how much air appears. If things start to run away as the engine gets hot (and it can with an unpressurised system), just turn off for a bit, let it cool and then repeat . When you get no more air out let things cool a bit, remove any excess coolant down to to the neck/thermostat housing level, fit the cap and close the bleed.
It's a faff but it works for me. Hope this helps!
Ian
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The wheels might clean up....as for the rest!?
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My experience of vapourisation was traced to the fuel boiling in the pump.
I have now replaced the mechanical pump with an electric Huco sucker and rerouted the fuel line to the carbs around the back of the engine.
For my sins, I do have K&N pancake filters, but have plans to rehome them in a new airbox with cold feed. (a winter project....maybe even this winter!)
+1 for heat shields.
Ian
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Puglet
Canley's gearbox diagram shows the roll pin. Item 39 Pt No. DS1908 (Layshaft dowel)
I recently watched a strip and re-assembly of a J type overdrive. Definitely no roll pins.
Looks as though your overdrive oil filter has done its job.
Ian
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Bobo
If you do end up fitting a remote kit, I would consider re-using the spherical ball if it is an original nylon one.
The balls in the kits are generally a moulded plastic and can be of questionable quality.
+1 for checking the direction of fitment of the bottom bolt.
Ian
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48 minutes ago, Iain T said:
Then there's centimetres a useless unit only used buy people who can't measure. In engineering it's millimeters and metres, centimetres don't exist.
Unfortunately that's what they teach in schools!
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The July issue of Classic & Sportscar P43-Pick of the Month, announces that 'Rimmer Bros has reintroduced a line of shock absorbers for Rotoflex equipped GT6s....... at £24.90ea built to OEM spec'
Might be of interest to some.
Ian
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On 06/06/2023 at 18:40, Dan lewis said:
the piston connected to the diaphram isnt pushing onto the little plate releasing the pressure
Dan
Do you have the spring under the little plate?
Ian
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Alan
I have had vapourisation issues with my GT6 when I was running the mechanical fuel pump and on one occasion when it 'failed to proceed' I took the top off the pump and could see the fuel boiling in the bowl, so this is a real issue, possibly made worse by modern fuels.
Your pump looks to be of a later design to the GT6 one, but probably fundamentally the same. I think if vapourisation does occur it will stop the pump from pulling fuel through. An air leak in the unions between the tank and pump is also a possibility, but you report that it runs ok when not hot.
I have now changed to Huco suction pump and have found this to have solved my original vapourisation problems.
Having said that, I recently had issues with physical blockages in the fuel lines due to a build up of rust particles. (TSSC article pending). You have said that your tank has been out and is clean. How about yer pipes?
Ian
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1 hour ago, Pete Lewis said:
hozpitalz
According to most people these days (particularly on the BBC it seems) it is pronounced hospi-tool! Winds I right up!
Ian
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15 hours ago, Pete Lewis said:
should be 0.9"
Or 0.090" perhaps!
Ian
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Aitch
I'm more familiar with Strombergs, but my starting technique from cold is full choke no throttle. Not a combination you list.
Ian
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An assorted pack of Flexoid gasket paper is always useful to have around.
https://www.amazon.co.uk/Flexoid-Gasket-Paper-Set-Sheets/dp/B00A1B6U6G
Ian
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Iain
My cap has a central brass rivet which holds on the rubber seal, through which there is a 7/64" (0.110") hole. IIRC on the top of the lower cap is a shallow cup, which is filled with wire wool, with the top section of the cap clipping over it.
I had mine re-chromed years ago and it one of the shiniest bits of the car! I have replaced the wire wool once or twice in my 46 year ownership.
Ian
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Iain
GT6/Vitesse 2-Litre WSM shows the vented cap in most but not all of the figures and photos in the engine section. eg Fig 4 Engine details (fixed parts) and Fig 82 Front view of engine, which is Vitesse specific.
My understanding of the vented cap would be that the breather can extract some fresh air mixed with the fumes.
Ian
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Dan
I would recommend that you do try and get the Smiths valve working properly if you can, as it is quite a clever bit of kit. Later cars didn't have this arrangement and plumbed the rocker direct into the carbs (bean counter intervention I suspect). Alternatively if you duplicate the breather arrangement of the 2500S with your manifold and carbs that should work OK.
In terms of the original set up:-
Measuring the top plate on my Smiths valve, it has a diameter of 74.2mm, a thickness of 1.22mm which allows it to sit inside the top lip of the aluminium body. The hole is 5/64" (1.98mm) and is 11mm from the edge. I see that you still have the wire clip.
The original manifold has a connection tail on the top/centre of the balance pipe (see photo) which connects to the base of the Smiths valve with the S shaped pipe. You have the later long branch inlet manifold (2500S IIRC) which is considered to be the best one, but yours doesn't have the tapping on the top, but does have something on the inside face (yellow) which I suspect is the vacuum take off for the distributor. There is a boss on the centre/inside of the balance pipe which could be used for the breather tail.
An L shaped pipe then connects from the rocker box to the side of the Smiths valve. In my case I have added a catch can between the rocker box and the valve, just to clean things up a bit (works too!), so the L shaped pipe is deleted.
The original oil filler cap is a vented design and has a plug of wire wool inside it to act as a filter. You have a non-vented cap. The pipe coming out of the rocker box is protected by a plate internally (to reduce the effect of splash) and this point should be checked to make sure it is clear.
Definitely worth you checking compressions in case blow-by is the issue.
Hope this helps.
Ian
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Ian
I have a Huco electric pump on my mk2 (as I was having hot running issues), which primes the carbs as soon as the ignition is switched on. (I do have 175 CD2 carbs, so not quite standard)
It's surprising how much fuel is heard gurgling into the carbs, so there must be a fair bit of evaporation from the float bowls.
Do you have the separate choke spindles or a starting box on the front carb?
Ian
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Johno
If as standard GT6, the front fitting is a steel hose tail. Photo attached showing front of inlet manifold with slightly rusty tail, plus new tail for comparison. (I haven't been brave enough to try and fit it yet)
This has quite a fine thread and can be difficult to remove without stripping the thread in the aluminium manifold.
Same goes for the banjo bolt at the rear...beware!
Ian
GT6 Boiled Over...
in Cooling System
Posted
Hi Kevin
Slightly disappointing news, but at least you know that all is well on the head gasket front.
I would certainly suggest running with the heater on hot for quite a long time after a refill, to make sure there is proper circulation and allow any trapped air to work its way out. I suspect you do still have air in the system. You mentioned you had elevated the front and managed to get some more air out. Was that with the engine running.
In your original post you said you had fitted a new radiator. It might be worth measuring from the top of the neck to the shelf of the lower seal, just to make sure that it hasn't been built wrongly. It does sound as though you might have rather flimsy hoses and this might be more of an issue on the Mk3 with the 13lb/sqin cap compared to the Mk1/2 with a 7lb/sqin cap. A standard top hose from Canleys or the TSSC shop should be fine though, without the expense of going to silicon.
The overflow pipe should be fine as the clear plastic, just make sure you have a half decent fit and/or hose clamp onto the radiator neck. If it is kinked near the top cut that bit off. 3/4 depth into the overflow bottle should be fine. My cold level in the bottle is at 1/2 depth, rising by approx 50mm when fully hot.
Keep at it and good luck. I'm sorry that I am not closer to Cheshire!
Ian