Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Tyre Pressures 2014 Roadster

2014 Roadster - tyre pressures.

Only had the car a few weeks, and I recall the Morgan agent recommending 2.4 front, 2.6 rear, but the manual gives completely different pressures. On the other hand, the manual is a little - erm - idiosyncratic and seems to want to cover a multitude of different models and I'm not sure that I'm reading it correctly.
I'd be very grateful for any advice.
Oh - and whilst I'm here, being a Morgan neophyte a couple of other things:

1. I'm taking it the fuel gauge is also idiosyncratic?
2. The temperature gauge / cooling fan relationship seems very efficient, the fan comes on when you might expect it in these hot weather days, and then cuts out presumably when it's happy. However, there's no movement on the temperature gauge that indicates that it's getting a bit warm and then after the fan has come on you see the temperature drop and then the fan cuts out. Is this the 'normal' type of indication?

Hugely obliged for any feedback.

My manual for 2011 treats all Traditional models the same for tyre pressures both front & rear: 22psi (1.52 bar)
Your 2.4 and 2.6 equate to 34.8 psi and 37.7 psi. MUCH too high for such a light car. Not sure of your “Morgan agent” as I dont know of anyone who has ever pumped them up like that!
Personally, I run at 24psi just to keep ground clearance up and to allow for slight seepage over time.
As far as temperatures are concerned, all Morgan gauges can be a bit irregular, but the main thing is that at least you can hear that the fan runs, so less chance of overheating.

A later thought…are you sure the agent didn’t suggest 24 psi and 26 psi, which would be nearer the mark?

You don’t say what tyres you have fitted - another Roadster owner will be along in a minute with much more precise advice.

I run our 2014 4/4 at 24psi on 165/80/15 Vredestein T-Trac 2 tyres.

I used to run the OE Continentals at 22psi. The 24 psi was recommended by the chap that fitted the tyres (Paul Harris) near the Belfry - sadly retired. He arrived at 24psi by looking at the side walls and inflating the tyres a little at a time until, to his experienced eye, they looked right.

This is a long winded way of saying that - you need them to be a lot lower but the actual value will be a matter of trial and error.

In your shoes, I would try 24psi all round next and see how the car drives.

As regards the fuel gauge, most people rely on the trip mileage. The gauge is notoriously vague.

I have found 22psi front and rear is ideal which exactly concurs with the manual. Any higher and tyres wear in the centre of tread on the 205/55 R16 option on my car. It also leaves the car with more comfortable ride on the bumpy roads we have in Norfolk especially when driving solo.

Much appreciate all of this feedback - thank you.
Very apposite comment from DJ, I wonder if I did mishear him - both previous motorcycles were in bar, the Audi is in bar as is the Mini - I wonder if this is down to me.
The tyres are Avon ZV7s if that makes any difference.

As a matter of interest? If you up the tyre size say from 165 to 185, do you increase or decrease the tyre pressure?silly question but just interested. Methinks decrease but hey I havn’t a clue. Sorry for thread drift but may help the OP.

Whizjet, My Roadster Sport runs 22front 24 rear on ZV7's if that helps.

Don't get fixated thinking the temp gauge on a 3.7 is saying anything accurate, the engine temp and fan controls are all quite sophisticated and controlled by the ECU

After swopping to an alloy rad the fan on my 3.7 comes on much less and has stopped the on / off / on cycling so I check the gauge far less and just spend more time concentrating on dodging potholes

FWIW I've never seen the temperature gauge move from it's slightly under half scale position once engine of my 3.7 Roadster is warmed up. This remained the case after fitting larger aluminium radiator the only difference being the two speed fan comes on to low speed far more rarely. I did record a peak OBD2 temp whilst on a dyno test of 112°C but didn't have the opportunity to see the gauge then. As Jon suggests the cooling system appears very resilient to all engine demands. Illustrated write up below of same below based on my observations:





The Roadster 3.7 V6 cooling system can be explained with the help of this Mustang engine cutaway image and that of lower inlet manifold. This appears to be moulded from a hard, hopefully non heat conducting, composite and is bolted in the V of the engine to seal with heads. It incorporates on the underside a hot coolant rail (tube) running horizontally down it's middle, mating to water jackets on rear of each cylinder head. Hot coolant flows forwards along the rail protruding to seal via "O" ring to a casting bolted to front face of engine (identified by blue label on cutaway) passing coolant via union to large bore top hose and radiator. The inlet manifold also has a hose union at rear fed from coolant rail to accommodate rubber hose feed to cabin heater matrix inlet (bottom union). In this way the hottest coolant in the engine reaches both the radiator and heater in most expeditious manner without the need for long rubber hoses. The casting provides the narrower bore permanent radiator bypass (part with cast-in text) running down to a mixing chamber below (shown as cutaway) to provide quickest warm up. The bottom hose of rad feeds to the thermostat housing bolted to bottom of casting mixing chamber with the temperature sensing side of enclosed thermostat facing inwards so directly onto bypass flow. This chamber also takes coolant from the return of permanently fed cabin heater circuit (see hose union) via a T piece which accomodates a head of coolant from the lowest point of header tank above.

When engine coolant warms sufficiently the stat begins to open allowing a cooled flow from radiator to be mixed in with the bypass and heater return. The turbulence from various flows into the mixing chamber mitigating the temp of very hot coolant from bypass circuit, the greatest influence being from the radiator cooled flow as the larger bore rad plumbing gives a preferred path for coolant, providing stat is open or partially so. The chamber outlet interfaces directly to pump casting inlet with actual water pump below, then pushing coolant upwards from lower part of engine block waterways. In this way the stat is able to control coolant temperature through a wide range of engine power demands (confirmed by near constant temp gauge) whilst always providing maximum temperature coolant to heater matrix.

The header tank accomodates two very narrow bore bleed/vent hoses from top of rad and top coolant rail with connection to latter seen adjacent to blue label. These assist bleeding and equalise levels throughout the system as coolant expands. The tank has markings for max and min levels with plenty of room above coolant level to allow for expansion as coolant heats when pressure within will rise, hence need for its pressure release filler cap, should system be overfilled. The upper mark should be checked to match top of radiator level since the clear plastic tank is a re-purposed moulding from a Ford Focus installation. Experience suggests coolant level is not critical although overfilling should be avoided.

The radiator, whether OE plastic side tank or conventional design taller after market all aluminium replacement, is further cooled when necessary by a two speed cooling fan. The only difference is it will run far less often with the latter, and when it does is far quieter due to fan assembly being attached directly to radiator without the OE cowling interface. The two fan speeds are ECU triggered by excessive coolant temperature via one of two relays dedicated to each fan speed, with a high wattage Ford resistor being brought into circuit to limit motor current for lower.

Thanks all, tyre pressures now sorted.

Interesting to note the posts regarding after market rad upgrades - was there a specific reason for this? I'd read somewhere about on particular Morgan having a leaking rad issue solved by this upgrade but the dealer told me not to worry.
I also asked about sump guards - any thoughts from anyone?

Oh, and whilst you're being kind enough to reply, how reliable is the fuel gauge and how reliable is the range function - on my K1600 GT, the fuel was extremely accurate but I'm sensing this may not be the case with the Morgan, and while the info functions are useful, they seem to have such low brilliance as to make them nearly impossible to read unless it's dark!