Follow-up on Hunter over-heating problems

[gouldsborough7]

Hi Guys
Back in August, I asked for advice re heating & plumbing snags, and made a few changes to my Hunter subsequently. Now we have experienced Winter weather, I thought it might serve a purpose to summarise what I did, and its effectiveness.

1) Several flushes of system carried out.
2) Tried bottle of water 'wetting' fluid in the radiator - not sure whether it made any noticeable improvement.
3) Fitted Ford Fiesta heater matrix in heater plumbing, mounting it just behind main radiator - definitely added to cooling ability - no more boiling problems in period before hot weather expired (great)& engine takes longer to reach operating temperature (maybe not so good).
4) Fitted bigger electric cooling fan (14inch diameter with curved blades, instead of original 12inch with straight blades. Now operates on manual dashboard button only. In traffic queues, produced noticeable drop on temperature gauge in say less than half a minute.

Any more future tweaks? Engine takes to long to reach operating temperature, especially in autumn ambient temperatures. Might plumb in a bypass circuit, operated by 2 manually operated washing-machine valves. This will allow the option of switching 'off' the water flowing through the Fiesta heater matrix, including the original reservoir box of water mounted under the main radiator.
Cheers
Mike

[Mike]

Re: Follow-up on Hunter over-heating problems

Mike

Very interesting - keep us posted on future experiments.
if the engine is slow to warm up, have you checked the thermostat is closing properly. Until the water in the engine reaches operating temperature the radiator should have no effect as the water should circulate around the engine only.

[greyV8pete]

Re: Follow-up on Hunter over-heating problems

Hi Mike. The heater circuit doesn't go through the main coolant thermostat. Heater supplies usually come out of the cylinder head and return through the bottom hose. Hence the slow warm up. More worryingly it may cool the engine too much when descending long hills as it will still be cooling the engine coolant even when the main T-stat to the radiator is fully closed.

Re the valves, you only need one in the "supply" pipe to the additional heater matrix. Older / classic cars used to have a separate manual shut off water valve for the heater, on or close to the engine and operated by a knob or lever from the inside of the car. Maybe you can source one of these?

With all those switches and knobs to pull it will be like driving a vintage car! ;-)
Peter.

[gouldsborough7]

Re: Follow-up on Hunter over-heating problems

Hi Guys
Mike, I replaced the thermostat at an early stage, with no changes to the problem of over-heating at that time. This was combined with the 1st of several flushings of the system.

Peter, yes I recognise the failings of an engine running cold for too long. I am planning the plumbing and valves as I write. My thoughts are to establish seasonal changes, i.e. winter - have the bypass circuit working, and spring-autumn - have the full amount of cooling in operation.

I think the whole problem stems from having a Ford Fiesta or similar rad in a streamlined body, instead of the full-blown jumbo required by a Granada engine, plus of course the limitation of air flowing through the engine compartment.

I'll let you know how the next stage works out.

Cheers
Mike

[gouldsborough7]

Re: Follow-up on Hunter over-heating problems

Part 2 of plumbing re-jig

Hi Guys

Thought some might like details of the last stage in the cooling system changes on my Hunter. Previously, as well as lots of flushing out the old crud, you will see in my notes that I fitted a larger electric fan, plus a supplementary mini-radiator (Ford Fiesta heater matrix) in the existing heater plumbing. I chose the latter, as it was relatively easy to cut into the heater piping and join up to a similar size on the Fiesta matrix. I hadn't space to fit a bigger main rad, nor did I want to spend £200-£300 on a more efficient aluminium one.

I found that, driving in the recent Winter weather, the engine took more than 10 miles to reach a normal running temperature. Can’t win – nearly boiled in the Summer heatwave, and now too cool in Winter! Consequently, I have fitted a bypass hose in the heater circuit, with some neat washing machine valves. So, with the valves set to ‘bypass mode’, the coolant remains stationary in both the original Marlin reservoir box (mounted beneath the radiator) and the Fiesta matrix. A circuit is still maintained between the Marlin heater matrix and its connection point adjacent to the exhaust mainifold.

In the Part 1 re-jig, I fitted another washing machine valve that allowed me to vent off any air in the system during the early re-filling with coolant. Marlin had not provided such an arrangement originally. During Part 2, I moved this valve so that it is now adjacent to the plastic header bottle on the nearside bulkhead and at the highest part of the system. While refilling with coolant and before re-sealing the system, with the engine running I can now direct any air or surplus water straight into the header bottle – saves a lot of mess, and is dead easy to do. I don’t have to fiddle around trying to bleed hot air/water around a loose hose connection.

I haven’t done much mileage with the recent dreadful weather, but on the few local trips indications are that the warm-up period is possibly down to say three-quarters of the previous mileage. Also, I have the bonus of an easy re-fill & bleeding operation if I have to drain the coolant for any reason.

Cheers
Mike

[greyV8pete]

Re: Follow-up on Hunter over-heating problems

Hi Mike. I am intrigued with your original Marlin reservoir box (mounted beneath the radiator) that you mention. I have a similar original Marlin idea on my V8 hunter but the box is in the heater line, sits on the bulkhead above the offside exhaust and so is purely to increase coolant capacity. Any chance of posting a couple of photos of your box? Peter.

[gouldsborough7]

Re: Follow-up on Hunter over-heating problems

Hi Peter
For your info, the reservoir box measures about 16 inches long x 3 inches square. I suppose it increases the coolant capacity by a couple of pints, but provides no cooling facility. I had a problem in getting decent pics, because of all the hardware in the way. The only good one is attached.

I wish my Hunter was a V8 instead of Granada, but beggars can't be choosers as the saying goes. I think when the weather improves I might take it to a tune-up shop to make it run a but better. Has an unfortunate flat-spot between 1500-2000rpm, but that's another story!

Cheers for now
Mike

[greyV8pete]

Re: Follow-up on Hunter over-heating problems

Thanks for the photo Mike. I realise now that your tank is also plumbed into the heater line. Mine wouldn't fit there as the V8 crankshaft pulley is nearly touching the rad! I upgraded my oil cooler to a 13 row plus a thermostat in the oil line back in the summer which did help the cooling a bit, but I still haven't done any more about the extra rad under the front which I think is the only solution now for mine. I guess with that fitted the increase in coolant capacity would mean that I could dispense with my tank in the heater line which would help initial warm up. Will follow this up when the weather gets a bit warmer and lying under the car is a bit more appealing! Peter.

[copperleaves11]

Re: Follow-up on Hunter over-heating problems

Another way of increasing coolant capacity,particularly with a V8 installation is to fit a Focus mk1 expansion tank,just behind the rad,on the offside.The main feed is is taken to a "T" in the bypass hose that goes from rear of water pump to heater. A small pipe connects from tank to top hose filler cap.A further small pipe connects to the original Rover expansion tank, thus retaining a 15psi cap.Modern cooling systems run around 1.2-1.3 bar 19psi approx which I thought might pop my heater matrix(original Mini).The end result increases capacity by 2 litres and the temp when in motion is a steady 85degrees (around 89degrees before).The electric fan will cut in if stationary long enough but nowhere as readily.Prior to fitting the above,I drained the system from the small tap at the side of the engine block.Allowing for the possibility of maybe 1litre remaining in the bottom of the system, there was only 6.25 litres that drained off.When the original Rover SD1 had over 11 litres of coolant and Range Rovers probably more it's not surprising that the standard Marlin set-up is marginal at best and after a few years wear and tear probably inadequate.Hope this might be of use to someone.David

[greyV8pete]

Re: Follow-up on Hunter over-heating problems

An interesting idea David if only....! My 3.9i V8 with the serpentine drive belt has a great lump of tensioner and an alternator in that space! In fact I have very little space left under the bonnet at all, as can be seen in the attached photos. That is why I keep coming back to the idea of putting an extra rad under the front as I know others have done. Apart from the complexity of the additional plumbing I am rather nervous about putting such a critical item in such a vulnerable location. Peter.

[copperleaves11]

Re: Follow-up on Hunter over-heating problems

Hi Peter. Looks from the photos like your alternator takes up quite a lot of the space. Mine is underslung on the nearside and therefore have more room in that area.

[copperleaves11]

Re: Follow-up on Hunter over-heating problems

Hi Peter.This photo illustrates our differences.Regards David.

[greyV8pete]

Re: Follow-up on Hunter over-heating problems

David. Many thanks for the photo. It has given me more ideas!
Mike. Sorry if I seem to have hijacked your thread but at least you know you are not alone with the overheating problem! Peter.

[gouldsborough7]

Re: Follow-up on Hunter over-heating problems

No problem, Peter.

At the other end of the spectrum, I am now waiting for a cold dry spell to take my Hunter for a couple of spins, and check just how long it takes to reach normal running temperature on 2 different days, with bypass pipe switched on for one run and off for the other. Will keep this subject alive a bit longer!

Cheers
Mike

[gouldsborough7]

Re: Follow-up on Hunter over-heating problems

Hiya all again
As promised, I have done a few comparison runs over the same territory and in similar cold weather conditions (5-7 degrees C - so heater was definitely switched ON), with conclusions below:-

1) With full amount of coolant flowing around engine, it takes up to 10-11 miles to reach normal operating temperature.

2) With bypass pipe operating (so no water is flowing through supplementary heater matrix or the original tank under the rad) the same journey takes about 6-7 miles to reach normal temps.

So a reasonable result for my efforts I think. I have now 4 options of cooling arrangements:-
a) bypass working & no fan;
b) full coolant in circulation & no fan;
c) as in (a) but with fan switched on;
d) as in (b) but with fan switched on.

I'll just have to keep my brain working in extremes of weather, so that I make the best use of these options!

Cheers
Mike