| Author | Message | ||
     Martin Cutler Prolific User Username: martin Post Number: 47 Registered: 10-2004 |
Hi guys, When I rebuilt the Freestone & Webb, I hooked up the heater core to the water jacket, but when I commenced pouring water inthe radiator, it all poured out the heater. I simply left the heater core hoses in place, and turned off the inline taps. My question is, if I connected the 2 hoses together, and opened the taps, ie, coolant is able to flow from the side of the head to the outlet on the water pump, does this aid circulation? Has anybody else short curcuited the heater core? I have not worried about rectifying the heater core itself as the heat generated by the firewall is quite high, and if it really gets cold, I turn on the demister fan, which works a treat. Marty | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 567 Registered: 4-2003 |
No, Martin, that will make the cooling very slightly worse, as the heater is a bypass circuit. It would reduce the flow through the radiator by a very small amount. No heater. Brrr !! At least the windsceren demister is a separate system. Incidentally, on a friend's MkVI I fitted a Bosch heater core which I bought from a wrecker for $20. There is an almost identical Delco unit, but they are flimsy like the one in a MkVI. Both the Delco and Bosch ones are the same diameter inside and out as on a MkVI, but slightly shallower by 2mm, and the Bosch one is far sturdier. It popped straight in with no modifications required. The heaters with these cores were very commonly used in generic aftermarket heaters on 1950s and 1960 cars when heaters were generally not standard equipment, especially in utes and panel vans into the mid-1960s. The one I bought was in an FB Holden standard sedan. Our one-time family Holden had the same type, but was a Delco with a flimsy core. I put a Bosch core in that car when the Delco one failed, so that's how I guessed it would fit the MkVI too. You may try the Morris Minor Centre for fun if you take your old core along as a pattern. Likewise, Rare Spares and othe old Holden specialists. Also, a radiator shop will help, and could possibly repair yours. They come out very easily. New genuine ones are incredibly expensive. RT. | ||
| Ashley James Yet to post message Username: ashley_james Post Number: 1 Registered: 2-2005 |
www.holden.co.uk or an old Morris Minor! | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 568 Registered: 4-2003 |
Nice pun, Ashley ! Of course I mean Holden cars, a highly successful General Motors subsidiary in Australia since the second world war. It shames the disasterous European Vauxhall and Opel subsidiaries. Holdens even export to the UK these days, including the Vauxhall Monaro (read Holden Monaro, a 5.7L coupé), and variants of the Vectra among others. The Morris Minor Centre is at Brookvale on Sydney's northen beaches. Minors often have the same heater retrofitted, as did the entire Morris and Austin range, and the MMC handles spares and repairs for them all. Martin will know them well as he owns an MG Magnette. RT. | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 10 Registered: 6-2004 |
Martin If you do put a new heater core in you might like to check the motor and the electrics. I made a long post to the Bentley Drivers Club website bulletin board about two years ago and you might like to look at it. It is in the Technical Forum under the heading Old Technical Forum Topic Mk VI Heater | ||
| Martin Cutler Prolific User Username: martin Post Number: 48 Registered: 10-2004 |
Thanks guys. I don't plan on replacing the heater core, as even on the coldest day, the car is still toasty warm. Maybe when I retire, in 20 years time, and am looking for something to do. Just a thought I had to move the water in the head a bit more. Cheers Marty | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 11 Registered: 6-2004 |
Martin The question of the interaction of the heater circuit with the rest of the cooling system is an interesting one. With the normal heating arrangements you can, of course, either have the hot water supply from the head either turned on or turned off. If it is turned on then there is a small flow through the heater back to the pump (the tap at the pump, if there is one, will usually always be open). This flow is limited by a restrictor in the feed pipe from the cylinder head and won`t be very big but it will be a bit cooler than the water feeding the heater depending on whether the heater fan is switched on or not. So, all other things being equal, the engine should run slightly cooler. But this assumes that the pump and the environment in which it works remains unaltered and it may be that this additional feed to the pump inlet from the exhaust side of the engine does affect the efficiency of the pump itself. There is some evidence (see the posts in this section of the forum under the heading MK VI Overheating Questions) to suggest that an additional feed to the pump inlet from the carburettor side increases circulation through the radiator quite a bit. This evidence is only based on pressure readings taken from the cylinder block drain tap position because I had no means of measuring flow directly and these readings are difficult to make and to interpret, and furthermore they were taken with the thermostat removed. But the outcome, in my case, was that I have left the thermostat out since cooling seems quite OK and the water circulation has probably been improved. The slightly longer time to get to a reasonable working temperature is acceptable and the better circulation has probably made life a little easier for the cylinders No 5 & 6 which is a benefit worth having. If you were to short circuit the heater by just connecting up the hoses the restrictor would still be in operation. But if you were to remove the restrictor (different pipe from the tap on the cylinder head?) you could then simulate changes in the restriction by adjusting the tap opening. If you could then fit up a pressure gauge as I did and get some readings we should all like to know what you find (with or without the thermostat). | ||
| Bill Coburn Grand Master Username: bill_coburn Post Number: 344 Registered: 4-2003 |
Laurie/ Your writings would be interesting to read and may be the means of preserving some of the cars. I wonder how we get access to them since I gather they are priviledged documents? | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 12 Registered: 6-2004 |
Bill Most of my write-ups are on the Bentley Drivers Club Website bulletin boards and some are on this forum. Only a few are in personal emails and these mostly get on to the bulletin boards eventually. At present there is a difficulty in accessing my stuff on the BDC website inasmuch as I was instrumental in reposting all the technical topics from the old website to the new one about a year ago and if you do a search by name of author for my topics you get all the ones I did not write as well. I have recently, having been given permission to do so, deleted the ones of no archive value which helps a bit. It is possible that sometime in the near future I may be able to put the old website topics separate groups according to car type which will make access easier. Almost all of my stuff is about MK VI and related vehicles. B420EY has been our only car for over 45 years and has over 410,000 miles on the clock. My interest is in passing on some of the things I have found out about keeping going in good order but not aiming at concours standards. | ||
| Martin Cutler Prolific User Username: martin Post Number: 49 Registered: 10-2004 |
Hi Laurie, How do you create an additional input on the carburettor side? I thought running without a thermostat was a no no for this engine, you suggesting dump the thermostat? I always let it warm up for quite a while before driving off, as the engine has not been apart, ie, original sleeves. At present motor warms up in less than 5 minutes, how long does it take with the thermostat out? Is the restrictor in the head behind the tap, or in the steel line running back along the top of the spark plugs? Cheers Martin | ||
| Martin Cutler Prolific User Username: martin Post Number: 50 Registered: 10-2004 |
Sorry Laurie, forgot to ask. Assume you are blocking off the by pass to take out the thermostat, how is this done. I read earlier about KC finding a rubber bung blocking the bypass. | ||
| Bill Coburn Grand Master Username: bill_coburn Post Number: 345 Registered: 4-2003 |
Thanks Laurie for sharing your experiences and knowledge with us on this site which is public. I have never quite understood how a group of so-called enthusiasts closet themselves within a club structure and contain the their knowledge experience and expertise within the membership group when the object (as I understand it) for all of these marque clubs is to preserve the cars. It seems to me the clubs are actually preserving themselves and if the cars are not owned by members they can rot. A strange attitude if I may observe!!! | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 13 Registered: 6-2004 |
Martin There is not a lot that I can add to the post I made on 9th Oct.2004 in this forum under the topic heading MK VI Overheating questions - this is the one which includes a copy of the email I sent some time ago to Norman Geeson. The last of the various tests I made, as reported there, was with the thermostat removed and the bypass open - that is to say the normal short hose was connected between the thermostat housing and the pump. Some pumps (maybe all?) have a tapped hole in the connection which mates with the bypass hose and this hole was open. I believe that this tapped hole was used to fit a restrictor in the very early days but I have never seen or heard about a restrictor being fitted in practice - a rubber bung in the hole will completely block off the bypass. So, with the thermostat out, the additional feed to the carburettor side of the pump came through the bypass hose and represented an unknown proportion of the water coming out of the head. But the total flow of water out of the head (ignoring that which goes via the heater and the induction warming circuit) seems to go up substantially because the pump works better. I know that this sounds odd but the pressure measurements seem to confirm it. I could not measure flow rates directly and checking pressure was the best that I could do. However, I must point out that the very satisfactory results I got, and am still getting, relate to a new radiator core (No 4 in the tests reported earlier). How the split between water going via the radiator and via the bypass will eventually work out is unknown but I would expect that when the radiator clogs up a bit then the proportion going through the radiator will be less and the overall advantage will be less. It would be nice if someone could test in the same way on another car. The pressure gauge I used read up to 5 lb/sq in, was connected to the cylinder block drain hole via a small hose up to a point close to where some wires go through a hole in the bulkhead. The small hose then connected to a smaller plastic tube which was small enough to be poked through with the wires and on to the pressure gauge temporarily (?) mounted on the instrument panel so that I could see it when driving. Regarding your query about the restrictor in the heater circuit - it is integral with the rubber hose end of the pipe attached to the outlet tap on the cylinder head where it reduces the diameter to about 0.25 in. My warming up time is about 2 minutes from startup and backing the car out into the drive. Since we are in suburbs there is only low power motoring for quite a while before we get to open roads. The engine is preheated by a 250 watt heater in the lower connection to the radiator (on a timeswitch) whenever it is cold or damp. If the pump really is a sensitive as it seems to be it might be even better to keep the thermostat in with the normal bypass arrangements and to provide a feed from the radiator drain connection near the dynamo into the connection on the pump where the induction heater circuit is piped in. This means altering the pipework to make the additional connection in a way which is sufficiently robust to stand up to the engine rocking movements. It is a funny old world - however much information and data you have you could always do with a bit more! | ||
| Martin Cutler Prolific User Username: martin Post Number: 51 Registered: 10-2004 |
Sorry Laurie, I'm a bit slow this morning :-) The additional feed is via the bypass hose. Water is pumped from the bottom of the radiator through the thermostat housing and up to the top of the radiator, so by having more coolant entering from the head, (most of the water coming into the pump comes from the block), it would draw more coolant through the motor. To me, that makes sense. | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 14 Registered: 6-2004 |
Martin I am not sure that you have the right idea as to how the coolant system works. Let me summarise what normally happens and see if this enables you to get a better picture. We start with the water at the bottom of the radiator. This feeds the main inlet of the pump on the exhaust side via a 1 1/4 In. hose. The water goes into the eye of the pump impeller and comes out at the back of the pump where it is joined on to the block. It then passes into a distribution pipe inside the block which has holes in so as to direct the water to the various cylinders and thus into the bottom of the block. From there the water goes up though the holes in the cylinder head gasket into the cylinder head from which there are three outlets, a small feed to the induction heating chambers near the carburetters, a small feed to the heater and the main outlet into the bottom of the thermostat housing. The thermostat is normally closed when the engine is cold and stops the flow into the radiator but leaves the bypass open. While the thermostat is closed the pump only receives water from the bypass so it circulates without any water going through the radiator and thus warms up quickly. As the water temperature rises the thermostat will begin to open the connection to the top of the radiator and in doing so begins to close the bypass. If the water temperature gets unduly high then the connection to the top of the radiator will be fully open and the bypass fully shut. Under normal driving conditions the thermostat is partially open to an extent which is dependent on water temperature and water flow so as to let the radiator have as much as is needed to keep the radiator thermometer steady at 78 dec C or thereabouts and divert the rest through the bypass directly back to the pump inlet without it being cooled. While all this is going on there will still be the small flows of water, only slightly cooler than it left the cylinder head from the induction heating chambers and from the car heater. Have a think about this and then come back with your further thoughts. | ||
| Martin Cutler Prolific User Username: martin Post Number: 52 Registered: 10-2004 |
Ok, sorry Laurie, will get to play with the Bentley on Sunday, so will report back after then. | ||
| Martin Cutler Prolific User Username: martin Post Number: 53 Registered: 10-2004 |
Success, Got the drain cock open at the back of the block, nice green coolant came flowing out at a good rate. Hmm, maybe there was no build up of silt? I then got the compressed air and water going, and after half an hour of constant flushing and pulsing with air, I had an amazingly large amount of rusty lumps of metal on the ground! I then back flushed the rad as well, getting a lot of muck out the top. Re-asembled and refilled with coolant, the motor sat right on 75 degrees while idling for 20 minutes - never done that before! I will keep an eye on it, and will have another crack at it in 6 months time, but for now I am very happy with the result. |
