Overheating on 16/70

[keithjecks]

Now that Winter is coming, I want to get to grips with the engine and cooling system of my 16/70. Its basic problem is that although it runs pretty well generally, with temperature guage reading about 75 deg C, when you go up a long hill, the temperature reading rapidly rises to as much as 100 deg. At the same time, the engine can lose power and start to spit back through the carbs. I have checked the guage, which reads about right.
   
   I have checked the plugs and carried out tests on the mixture (both by using a colortune, and using the old technique of raising the piston in the carbs with a screw driver). All these indicate the rear most carb to be running lean and the forward one running rich (the one in the middle being about right so far as I can tell). I have adjusted these by unscrewing (to richen) the big spring loaded nut on the bottom of the carbs. I have not tested the car on the road since, but was surprised at the fact that I had to move the 'weak' carb as much as 8 'flats' on the nut (i.e. more than a turn). I thought the mixture control would be more sensitive than that.
   
   Issues/ questions:
   
   1. The water pump is driven off a pulley attached to the fan, via a split pin. Is that really all that should connect the pulley to the water pump?
   2. My radiator shows pretty even temperature across its width, although on the o/s one or two inches the temperature is much lower whe the engine is hot. I am going to try some radiator flushing liquid to see if it clears the blockage, but even with this I am surprised that the temperature of the outlet from the radiator is only 5 deg less than the input. Does this imply that the fan is not doing its job? It appears OK to me, and it looks like water is circulating if you remove the filler cap, but I am aware that the fan belt is a modern rubber item rather than the period leather jobbie so could be slipping I guess.
   3. Using an infra red thermometer, I have checked the temperature at rest of the block (because if there are any blockages I guess I would see local over heating?) Anyway, as far as I can tell, the temeratures are pretty even.
   4. There appears to be some wear in the carb linkage. The centre and rear carbs open together, but there is slack causing the front carb to open later. This looks to me to be a result of the throttle butterfly bearings on the centre carb being worn. Is that right/ does it matter in that the car runs well except for the over heating/ spitting back problems?
   5. Is there anyone in the Surrey/Kent area experienced with these engines that I can take it to who would be able to tune it properly and tell me what is normal? That is one of my key problems: I am experienced in modern cars and do not really know what I should expect in a pre-war car.

[Robin A Woolmer]

It would seem you must have some form of blockage in the system, you could remove your radiator quite easily & have it cleaned out by a radiator specialist & then power flush the engine in both directions after removing the water pump on the front of the head.
   It is going to be a messy job, if this does not help then you could possibly have a blockage in the water ways to the head which would require you to remove the head!
   If you would like assistance from an AC Engine specialist then Jon Sichel is located in Penshurst Kent tel/fax 01892 863 280, Jon can also rebuild your water pump if needed.

[administrator]

The rad on my 16/70 was totally blocked so I had a new one made and combined with one of Robin's new water pumps, the car has shown no signs of overheating so far.  The insides of the thermostat were missing so I have an empty casting - I obviously can't comment on how adjusting the thermostat would affect the set-up.

[keithjecks]

Well, I took the car to the festival of speed yesterday and she is still up to some of her tricks! Basically, the car runs about 10 deg hotter than I think it should. On the flat it shows about 80 deg when cruising at 45-50 MPH, which rises to 95 when idling in traffic and more when tackling steep hills. I have now had the engine apart and can be certain that it is running correctly and that there are no blockages in the block or head. The pump is OK, so it seems that the radiator must be the culprit. Who do we know that can look at the radiator and tell me if there are any blockages and whether it needs to be rebuilt?

[Robin A Woolmer]

Keith
   I use a company in Hampshire called Abbey Heat Transfer Ltd 02380 653 331 they will test & clean the radiator for you & if you require it will fit a new core, i have had this done & on my special rad they fitted an uprated core also.
   They are or were not overly expensive & did a good job.
   They have been in the Southampton area for many years.
   
   Robin

[keithjecks]

That sounds ideal, thanks. How much should I expect to pay? My inclination would be to get them to upgrade it because I gather the cooling has always been marginal, and that modern petrol burns hotter. Is that correct?

[1936ACE]

Hi Keith.  I got Bagshot radiators to rebuild mine with a new core.  Very helpful and friendly service at a fraction of the price I'd been quoted elsewhere.  Together with one of Robin's nice pumps all seems to be going well with no embarrassing leaks and running at about 150 degrees.
   
   Regards,
   Mike

[keithjecks]

Do you remember how much you paid, Mike? Abbey Heat Transfer want £1350 +VAT, which seems far too much to me!

[Robin A Woolmer]

Keith
   I paid no more than a couple of hundred £ but it was some years ago, £1350 is very high!
   Robin

[keithjecks]

Bagshot radiators are guessing £300 - 400. they will give me a final quote Thursday when I drop it off to them. At that price, it is more interesting!