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Engine overheat
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Rollmop



Joined: 23 Dec 2016
Posts: 14
Location: Market Drayton, Shropshire

PostPosted: Sat Aug 08, 2020 10:54 am    Post subject: Engine overheat Reply with quote

I have a recurring problem of a near overheat on my Triumph Mayflower..
The block galleries are clean, the head is also, the radiator is new and the water pump and thermostat function correctly so I canít understand why the problem occurs. I read somewhere a number of years ago that an old engine could run hot if the timing was out but canít remember what the cure was, advance or retard. The current timing, 2 degrees before TDC, is spot on and the automatic advance on the distributor appears to be ok. With the very limited 38hp from the engine I donít want to loose any power unless I have to but I would like to drive a little easier and not have to keep my one eye on the temperature gauge all the time. It could be a folk memory but my first ever car, another 52 Mayflower, did not have an overheat problem and I used that in London traffic for 2 years in 67 & 68.
Any ideas would be greatly appreciated.
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Rick
Site Admin


Joined: 27 Apr 2005
Posts: 21620
Location: UK

PostPosted: Sat Aug 08, 2020 11:52 am    Post subject: Reply with quote

Hi,

Is it possible that the mechanical fan blade assembly is on the wrong way around? Just a thought, it might not make enough of a difference.

Although I don't like the look of them, is there space to hang a small electric fan in there to supplement the mechanical fan?

Is the fan belt slipping slightly, just enough to reduce the effectiveness of the pump?

RJ
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Rollmop



Joined: 23 Dec 2016
Posts: 14
Location: Market Drayton, Shropshire

PostPosted: Sat Aug 08, 2020 1:29 pm    Post subject: Reply with quote

Hi there, thanks for the input. Fan belt and direction of airflow checked and all ok. I have an electric aux fan fitted in front of the radiator linked to a thermostat to cut in at 80C and this is on almost constantly. I thought a better quality electric fan might give a bigger air flow but I am wary, with only dynamo charging, that the power consumption might exhaust the battery.
The top hose temp with the thermostat open is 79C and the bottom hose temp is 58C so there is an effective drop across the radiator. I think it is the heat input from the block and head that is the problem hence my question as to whether the timing can make an engine run hot.
RF
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Keith D



Joined: 16 Oct 2008
Posts: 1009
Location: Upper Swan, Western Australia

PostPosted: Sat Aug 08, 2020 2:00 pm    Post subject: Reply with quote

Hi Rollmop,

Is the car actually boiling? I presume that you are learning of the high running temperature from your temp gauge. My Austin A40 has a Smiths temperature gauge that is a sealed unit with it's capillary tube and sender unit. I would assume that the Mayflower would be fitted with a similar type of setup. If the tube is damaged in any way, incorrect indication of temperature can result. Perhaps the engine is actually running within its correct temp range.

Keith
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alastairq



Joined: 14 Oct 2016
Posts: 1462
Location: East Yorkshire

PostPosted: Sat Aug 08, 2020 2:04 pm    Post subject: Reply with quote

Today's petrol will cause our old technology engines to run warmer than of old.

As a suggestion, try advancing the ignitin timing at tickover, a few degrees more?

This should be accompanied by a road test, engine under load [I won't mention the word, ''acceleration'' in this instance.. Smile ] Listen out for pinking up to around 3000 rpms...if pinking is heard, retard the ignition timing by a smidgen [hi tech engineering term...honest!]....until pinking just goes away.
This may well result in a basic timing figure of more advance than your 'book' says.....[remember, the book was written 70 years ago?? Petrol is very different today to what it was back then]
The problem is, your engine's exhaust temperature is hotter than it once was.
To get the full picture, I suggest investing in the book linked below....which are the results, and some conclusions, of tests carried out by Manchester University on an old design of engine [MG XPAG]...
This will explain the results, and tell you what is currently going on in your old engine...and what might be done to mitigate the bad effects.

[BTW, if you wait until E10 petrol is available, you might find your Triumph runs better with some ethanol in the fuel?]

https://www.veloce.co.uk/store/Classic-Engines-Modern-Fuel-The-Problems-the-Solutions-p151478624

The book can be had cheaper elsewhere....but the contents will help dispel much of the urban myth surrounding modern fuel, and old engines.
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Ray White



Joined: 02 Dec 2014
Posts: 4085
Location: Derby

PostPosted: Sat Aug 08, 2020 2:42 pm    Post subject: Reply with quote

I understand it's the ethanol in petrol that causes the older engines to run hotter. I would also recommend Paul Ireland's book. Alternatively you could follow the series of articles published in the on line magazine 'Totally T Type 2'.

The method of timing adjustment was what served the old school mechanics well for many years. I always used that method on my Triumph GT6 - and it was recommended in the manual!

The other thing is that petrol today has a completely different burn rate but the effects can vary from one engine to another which is confusing.

Personally, I am a fan of exhaust heat wraps which might also work for your car.

Then there is always the use of this....
https://www.evanscoolant.com/how-it-works/
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alastairq



Joined: 14 Oct 2016
Posts: 1462
Location: East Yorkshire

PostPosted: Sat Aug 08, 2020 3:29 pm    Post subject: Reply with quote

Quote:

I understand it's the ethanol in petrol that causes the older engines to run hotter

Only because, by adding ethanol, the mixture in a carburettor is weakened.....countered by increasing jet sizes, or re-tuning if a variable choke-type carb [SU, etc]...weak mixtures can lead to hotter running.
Since current petrol may, or may not, contain no more than 5% ethanol [some will have less than that..apparently it can vary on a daily basis]...the wakening effect has probably not reared its ugly head yet? E10 may well show up more ...?
Modern ECU controlled engines simply automatically compensate.

What may be seen by the OP is the effects of running 'winter' petrol in the engine's system....?

May I suggest the OP runs his current fuel tank down, and plonk in some of today[s fresh petrol? This will evaporate less readily than winter petrol.

Exhaust heat wraps have their place, in reducing underbonnet temperatures...but the Manchester tests showed that most of the heat that affects the fuel in the carbs comes from heat soak via the valves....
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Ford Mustang coupe, 1967, 6 cylinder auto.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ray White



Joined: 02 Dec 2014
Posts: 4085
Location: Derby

PostPosted: Sat Aug 08, 2020 3:57 pm    Post subject: Reply with quote

alastairq wrote:

Exhaust heat wraps have their place, in reducing underbonnet temperatures...but the Manchester tests showed that most of the heat that affects the fuel in the carbs comes from heat soak via the valves....


I don't know if I should admit to this but I once made an exhaust system for my Austin7 Swallow from copper pipe( with a half size steel silencer mounted across the back) and wrapped it to keep in the heat.

I am not sure if it was even legal to use copper tubing but the performance improvement was quite noticeable.

I now have stainless steel made to the correct pattern. Expensive!


Last edited by Ray White on Sat Aug 08, 2020 4:32 pm; edited 1 time in total
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MVPeters



Joined: 28 Aug 2008
Posts: 751
Location: Northern MA, USA

PostPosted: Sat Aug 08, 2020 4:29 pm    Post subject: Reply with quote

L J K Setright once wrote that, with the right materials & dimensions, one could make any exhaust sound like anything you like. His analogy was to brass band instruments. A Mini could sound like a Bugatti!

Rollmop
I'm a huge fan of using a vacuum gauge to set timing on older engines. If you have an available vacuum port on the manifold it's the most inexpensive way of determining what's going on inside the engine. With a little experience, you can detect lots of other things too. If you choose to use one, get one with a 270-degree range if you can.
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Ray White



Joined: 02 Dec 2014
Posts: 4085
Location: Derby

PostPosted: Sat Aug 08, 2020 4:35 pm    Post subject: Reply with quote

I have a vacuum testing gauge and also a basic gas analyser. These things can be picked up cheaply now as cars have become so environmentally constrained.
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Kenham



Joined: 12 Mar 2012
Posts: 195
Location: Kent

PostPosted: Sat Aug 08, 2020 8:23 pm    Post subject: Reply with quote

What temperature does it go up to , 80c does not seem to be overheating, sounds like the radiator is working well with your description.
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Ray White



Joined: 02 Dec 2014
Posts: 4085
Location: Derby

PostPosted: Sun Aug 09, 2020 1:15 am    Post subject: Reply with quote

Kenham wrote:
What temperature does it go up to , 80c does not seem to be overheating, sounds like the radiator is working well with your description.


I am with you. The figures quoted seem fine to me.
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alanb



Joined: 10 Sep 2012
Posts: 508
Location: Berkshire.

PostPosted: Sun Aug 09, 2020 11:01 am    Post subject: Reply with quote

The boiling point of water rises with pressure at 8 psi boiling point is approximately 120c so 80c is quite a long way from boiling.
Ethanol was used in petrol before lead as a performance enhancer so advancing the timing a couple of degrees may help, also if the mixture is a little weak it can cause overheating
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lowdrag



Joined: 10 Apr 2009
Posts: 1413
Location: Le Mans

PostPosted: Sun Aug 09, 2020 1:29 pm    Post subject: Reply with quote

Sorry if this seems silly, but could the problem be a gauge? I've had poor senders which gave wrong readings. The gauge was off the scale but the car itself - and the temperature - were fine. I see 80C has been mentioned, but was this confirmed independently.
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alanb



Joined: 10 Sep 2012
Posts: 508
Location: Berkshire.

PostPosted: Sun Aug 09, 2020 11:06 pm    Post subject: Reply with quote

Capillary action gauges should have the transfer tube between the capillary bulb and gauge well clear of the engine or other hot parts that could influence the gauge .
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