Race Engine Forum UK

Guy , as you may remember I had a constant heat problem with my 131.

The new engine I am building will have - as you suggested an in-head low temperarture thermostat. I also plan to completely close the small circuir of the coolant by removing the old "controlled by-pass thermostat" housing , connecting the hose from the radiator directly to the water pump to block , block off the T - piece from the disconnected old thermostat. This way all the coolant will flow directly from the radiator to the waterpump and block, and from the block to the radiator.

There, at least technically is another way of doing it : to remove the thermostatt from the old housing , install an in head thermostat and keep all the rest. This way the by pass coolant curcuit will remail , but the coolant flow will be controlled by the thermostat in thne head. This srtrikes me as a half solution unless there is a special role that the by pass curcuit plays. Logican=l analysis suggests thatvthe by pass was designed to preven overcooling of the engine. In a case of a race use of the car there seems to be no sense in keeping this at all as the car is never used in cold weather (garaged all winter) and on rece track or rally too cool is never a problem, just the opposite.

Could you confirm , comment.


Also, I noticed that my T- piece connecting coolant flow from the block and standard external thermostat housing with the radiator is installed in a way that causes my concern.
To check that without draining the coolant just yet I have taken a similar spare piece form the garage shelf
and noticed that on the left( (from external thermostst housing ) the T- piece is fully opened (unrestricted) with almost 30 mm opening
but on the right (to the radiator the opening is half the size which severely restricts the coolant flow ( probably as much as 75% ).
Assuming the actual openings on the installed T-piece is the same - this is appears drastically wrong. If anything this should be the other way. Maybe this has been installed upside down. Before draining the system I want to clarify proper installation.

Could you help ?

Is it possible that the installed T-piece came from a different engine? Some 124 spider version ?

Now, I assume the T- piece actually installed on the engine has been installed properly , and the openings are right ( small left and big right ), but if not I will kill the mechanic (oh, was it me ?) !

Miro

PS: Is this a proper location for a coolant temperature sensor ? Shouldn't it be in the head?

M

The earlier engines had an in head thermostat and no T piece just a single pipe coming out of the head between the cams. Using one of those would be the easiest solution.

see here

Thanks,

having read this I bought the appropriate part on e-bay .
Miro

There is no problem at all in using an in-head stat mounted at the front on that engine provided you observe a sensisble warm-up period.

The 3 way stat circulates coolant round the head but not the block in an effort to er, 'harmonise' the thermal expansion, because of course the head heats up much quicker from cold than the block - and the block needs to heat up fast so as to stop the pistons from scuffing. It is a good system but does call for a lot of hose.

An in-head low-temp stat (74 deg C or so) should always have an air bleed hole and their design makes it easy to adjust the operating temperature of the engine - simply drill additional bypass holes in the thing.

The early TC units (1438/1608) had in-head stats like the one you bought, later they were changed to external ones and later still the coolant outlet elbow was moved to the back of the head which is a better location. The coolant circulation (and associated heat dispersion) is superior; there is a tendency for the cooler liquid not to reach the furthest extent of the unit when the outlet is right above the pump.

The OE T piece can be welded-up on one side and the top (hot) hose run straight to the top of the radiator. The elbow from that model can also be held on a fixture in a lathe and turned down (as per engine on the cover of my TC book) and the hose slipped straight on it. You must ensure that the hose clip doesn't foul the cambelt.

The lowest external stat I have managed to get (recently) is 80 deg C full open which is way better for a competition engine than the standard 95 deg C cited for most F/L models.

GC