14 replies to this topic

[MontpellierVanMan]

Any informed suggestions about this set-up please ? I'm using an MPI head LDF105200

 

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on an earlier A+ block, and am reluctant to abandon the pre-MPI thermostat cover that was used with my previous head since all the shrouds and brackets and hose etc line up nicely.

 

 

I'm guessing the MPI has a sandwich-plate or w.h.y. since the seating in the head is smaller than the previous one, and in order to get the thermostat in the "conventional" position I have had to machine its periphery and secure it with a stainless cap-screw - which will work fine, and forever, if necessary.

 

The one shown has actually been "emptied" since it once got stuck shut, and it's 33°C out here at the moment so a thermostat is not a major preoccupation  ............

 

 

 

 

(The one shown, incidentally,  is remarkable for being a part supplied by one of The Usual Suspects, a few years ago, which in my naivety I failed to spot was not the correct type with the little bleed-toggle, which enabled me to crack a head when the cooling-circuit failed to bleed and I drove it around the block ............... stupid, but incredible that one-make / one-model parts suppliers can't even get a detail like that right.)

 

Two questions :

 

1. Should I just get something like a standard 82° 'stat GTS104

 

https://www.minispar...|Back to search

 

and trim the periphery like I've done with the current one, and re-fit it with the screw, or is there a more subtle reason why the MPI uses different housing ?

 

2. What is the difference between using a chopped thermostat like the one shown, and the "official" blanking sleeve 11G176 which has a quite different  shape and - presumably - effect ?

 

https://www.minispar...|Back to search

 

Many thanks in advance.

Edited by MontpellierVanMan, 08 September 2016 - 08:40 AM.

[Spider]

The first one I got 'caught out' as I didn't realise that these MPI heads had a smaller orifice for the T'stat, after looking in to it, like you I found out the right fittings etc, however on that first one, I had not time to waste so I just trimmed down the T'stat. That was some 4 years and 35 000 km ago and no issues since.

 

I did the next couple by machining a register in to that that is there, so it would fit as per conventional pre-MPI heads, however I found these were a liitle too easy to weep coolant as the gasket face gets pretty thin near the studs.

 

I've now gone back to plan A and trim the T'stats. I haven't bothered to 'pin' them as you've done though, but do trim them quite neat.

[MontpellierVanMan]

Hi Moke,

How do you stop them coming loose without a screw ? I took mine down with a flap-wheel, the groove is a convenient guide for the required diameter, and for what it's doing it didn't seem worth making a jig for the lathe.

So it's a snug fit in the rebate but the alloy housing over the top doesn't have any grip or push downwards - are you just relying perhaps on the gasket ?

R

[nicklouse]

2. As it has not been covered yet.

The sleeve/plate was developed by BL to do two things.

Improve the circulation of the water getting down to the far end of the engine and also (supposedly) to reduce the chances of cavitation of the pump (well the water by the pump)

The first point was that it is to be used on engines that no longer have the bypass hose. But White the stat. removed they were having heat issues on 3 and 4 cylinders. Using a cored out stat. like your have was better than none but ST wanted better and the sleeve is what they come up with.


Back to the head. What does the standard MPI head look like in the stat. area? I have never looked at one but I do have new unused sandwich plate and used top part that was used on a A head and stat. With no issues. So I am thinking that a recess in the stat. housing would be an other (easier) solution.

On the hill climb car I run a stat. With a few extra holes in it and a hose from the take off by cyclinder 4 back to the lower hose as I want to build heat up fast and then bring in the cooling from the rad.

Will be going to an electric water pump later instead of the mech one. Or might add a secondary one just for shut down cooling.

[Spider]

Hi Moke,

How do you stop them coming loose without a screw ? I took mine down with a flap-wheel, the groove is a convenient guide for the required diameter, and for what it's doing it didn't seem worth making a jig for the lathe.

So it's a snug fit in the rebate but the alloy housing over the top doesn't have any grip or push downwards - are you just relying perhaps on the gasket ?

R

 

It's just snug in the head. From memory, although it's reduced in diameter, it's still too big to rise through to the T'stat housing.

[Spider]

This is the factory low-down on the Blanking Sleeve (3rd Paragraph) as well as some general advice if overheating is a problem;-

 

 

and I note what they say in regards to sealing off the by-pass.

[MontpellierVanMan]

The reduced diameter of a modified thermostat is quite a lot smaller than the 12G103 thermostat cover's bore at that point so it would otherwise float around, hence my pinning it.

 

I thought I should have machined a rebate into the new MPI head to enable the thermostat to sit in the conventional position, and can't see why that should make it any more prone to stud leaking since the 3-point footprint of the cover is identical to the pre-MPI layout, no ?

 

I remain puzzled by the Blanking Sleeve shape 11G176 and the idea that this works better than a chopped thermostat - are we accepting then that, ideally, and if our engines were only ever "hot", that 11G176 gives the best cooling performance and is therefore better than an "open" thermostat ?

 

These discussions may seem a bit irrelevant for some contributors, but after 2 hours at a constant 85mph on Motorways here, with the afternoon temperature this last week at 34° C, the oil-temperature on my 1380 gets up to 120°C and the water rises from 100° C to 110° C when there's a bit of a head-wind or a rise, so I'm concerned to get the cooling as good as possible.

 

(Stack guages, Stack sensors, I believe these figures to be accurate ; oil-cooler and thermostat being fitted this week.)

 

As an aside, and in contradiction of some apparently erudite suggestions I've read in the past, I have proved - to my own satisfaction at least - that there is NO way you can run my Mini without the mechanical fan ; it is NOT "useless" above 30 mph, and the air-flow through the radiator due to the speed of the car is NOT enough to keep the engine cool.

 

My attempts with no mechanical fan included some clever baffling and ducting to get more air through the radiator, and yet I spent most of the 1.500 km of testing with the electric Kenlowe fan in the wing working its balls off and the engine T° up on the 100 - 110 range despite rather clement spring temperatures.

 

Once I put the mechanical (yellow) fan back on, I would guess engine temperatures dropped by about 10 to 20°, like-for-like, and remained in the 90 - 100° range with the fan (set to come on at about 105°) remaining silent except for surges in halts for traffic - and this in average 30° ambient temperatures last week.

 

PS - Like Nicklouse I am experimenting with a little Davies-Craig (actually Bosch) pump in the heater-circuit, which is wired to come on when the Kenlowe switches on - I believe I am close to being able to say that this solves the problem of the heat-surge from the block that keeps the Kenlowe on for ridiculously long periods due to the fact that there is actually no churning going on within the engine ; since I did this, on shut-down the Kenlowe comes on for a much shorter time, then very occasionally for a second short burst, suggesting that the little Bosch is generating some genuine flow through the radiator and engine to avoid spikes in the block T° ?

Edited by MontpellierVanMan, 08 September 2016 - 08:41 AM.

[Spider]

Yes, securing the Thermostat in some way would be better than what I've done and done on a few now, but - touch wood - so far, no issues (famous last words).

 

I have to say (and I think I've talked about this elsewhere on the forum) I do not like Blanking Sleeves or 'Open Thermostats' one bit. My reasons for this is that if everything is working as it should, then the Thermostat shouldn't impose any 'restriction' on the cooling system capacity. IMO, Temperature stability if far FAR more important that trying to achieve some wavering low temperature. For example, I wouldn't be too worried if the engine ran at 95 degrees all day, every day, but I would be concerned with a Temp that's going from 65 to 95 and cycling like that every 15 minutes or so.

 

With a Blanking Sleeve or Open Thermostat, the Temperatures are up and down all day, like a lift driver's backside. In the cooler weather, the heater doesn't get toasty either.

 

Hottest sustained Temps I've driven in were 53 degrees for around 6 - 8 hours, not a comfortable day, though we pressed on at a slightly reduced speed of 100 kph (circa 4000 RPMs) The Temp gauge did climb from it's usually 85 to 92, but that was it.

 

Back to Blanking Sleeves. As far as I have been made aware, they were introduced for Competition purposes for fear of a failed Thermostat during an event. We did have one in the Race car for a short period, but found we couldn't keep the temp in it, so went back to a 74 T'stat.

 

For the road, all year round, I run an 82 degree Thermostat.

 

Not surprised what you found with the fan!

Edited by Moke Spider, 08 September 2016 - 09:35 AM.

[nicklouse]

would be interesting to see how (and which electric pump) you have plumbed it in.

 

Oh the airflow and air pressures in/under and around a Mini.

 

it has been well documented and is not what many people expect. side mounted rad and no mech fan = no (or very little) air flow through the rad.

[nicklouse]

This is the factory low-down on the Blanking Sleeve (3rd Paragraph) as well as some general advice if overheating is a problem;-
 

 
and I note what they say in regards to sealing off the by-pass.

I have always loved that paragraph. It says two things that could be confused with each other.

[Spider]

 

and I note what they say in regards to sealing off the by-pass.

I have always loved that paragraph. It says two things that could be confused with each other.

 

 

It's subjective that's for sure

[nicklouse]

Back to the MPI head are the first images of the head as is? Or has it been modded?

If it is as then I thing I would have just machined a recess in the cover to take the full size stat.

[nicklouse]

and I note what they say in regards to sealing off the by-pass.

I have always loved that paragraph. It says two things that could be confused with each other.

 
It's subjective that's for sure

Not really as are is two parts of the bypass. The one we know and love and tend to blank off. Then there is the part in the casting.

Which takes us back to the question my Monty. Why is the sleeve the shape it is. On the MPI there is no need for it but for heads with the bypass cast in it.

[Spider]

I've never bothered to go too far with them and I have serious doubts about how they flow. For all that I've ever seen and is clear from your photo here is that they blank off the By-pass, not completely seal it, but close enough.

 

A Pump Designer once pointed out to me that the location of the By-pass inlet in to the Pump itself will introduce the on-set of cavitation soon (at lower revs) and by fitting the blanking sleeve this maybe how they work.

 

IMO and from the very limited tests I've done, fitting an open thermostat plate is more effective (as well as blanking off the By-pass properly). Also IMHO, they are a dumb thing (for reasons set out in this thread) that I've never bothered to contribute too many brain cells too either.

Edited by Moke Spider, 10 September 2016 - 09:14 PM.

[nicklouse]

I did spend some time thinking about it 20 years back and put it back in the box of spares.