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PostPosted: Fri Mar 20, 2020 8:37 pm 
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Joined: Sat Jan 11, 2020 12:55 pm
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Car Model: 1972 99L 2 door
Hello,

As per title really - I have grabbed the attached pic from an online manual for the 1977 Saab 99, it is page 22 and shows the cooling system diagram for the B engine.

I would really like to see a bigger or better quality scan of the diagram if anyone could help please? The arrows show which way round the engine the coolant flows but i can't quite make out which way the arrows point in and out of the inlet manifold / pump area. :?

If you have seen my rolling restoration thread, you will have seen my efforts to get the EWP installation making heat inside the cabin. It is not going so well so i am in search of a flow diagram to see if it can point to where it might be going wrong.

I seem to be struggling to identify where the supply to the matrix comes from on the engine. I have just added a supply from the thermostat housing on the basis that this is always going to be one of the points where the coolant is warmest (ie before it goes through 'stat to radiator) but what this seems to have done is allow water from the bulkhead end of the inlet manifold to go through the heater matrix first. :?

It doesn't really matter which way through the matrix the water flows as long as it flows enough hot water to exchange into hot air inside the car, the concern is that by interrupting the flow, i am reducing flow somewhere else...

Overall coolant temperature is around 75deg C usual driving but heater hoses get to a maximum of 30deg C. not enough.

thankyou! :)


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cooling system.jpg
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PostPosted: Fri Mar 20, 2020 9:23 pm 
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This is off the top of my head and so may need correction after I've had a look at the manual!

Basically to get a flow through the matrix you need a slight difference in pressure between the inlet and outlet of the heater.

As I remember it, hot coolant going to the heater leaves the engine from the hose on the inlet manifold and is directed to the heater valve. This is coolant from the outlet of the water pump and is higher pressure. If the heater valve is closed it can return back to the water pump via the restricted 'tee' connection in the hose. This maintains coolant circulation around the engine without going through the radiator while the engine is warming up and the thermostat is closed. If the heater valve is open then most of the coolant will tend to go through the matrix as this is an easier path than through the restricted path.

Coolant leaving the matrix returns to the inlet (low pressure) side of the water pump via the tee connection in the hose from the header tank to the water pump inlet.

I haven't studied how you have plumbed in your electric pump but suspect that the outlet from heater is no longer on the inlet side of the pump and so not seing any pressure differential.


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PostPosted: Fri Mar 20, 2020 9:33 pm 
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Car Model: 1972 99L 2 door
Hi Pete, thanks for taking the time to write out that answer - much appreciated.

I also think there is an issue with pressure difference, the direction of flow through the matrix has actually changed with my 'new' take off, that was unexpected but shows it is quite finely balanced.

My issues are almost certainly down to having an electric pump. It is fitted in the return hose from the radiator so pushes water into the connection on the pump cover usually connected to the header tank. Once in through that hole, the water is free to flow whichever way it fancies rather than being directed off the impellor of the original pump.

Will add a photo of how it is now to see if that may help.

The other issue is that the engine bay has the 1972 triumph engine heater matrix which may well also be connected differently to the B engine ones as far as I know!


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PostPosted: Fri Mar 20, 2020 9:37 pm 
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Car Model: 1972 99L 2 door
Pics will have to be tomorrow, for some reason I've not got any pics of this on my phone at the moment. I like to take pics as I go to help reassemble things when the time comes.


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PostPosted: Sat Mar 21, 2020 7:30 am 
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Car Model: 1972 99L 2 door
photos. :D

In the overall engine bay photo, you can see the electric pump hiding under the air intake hose.

The current circuit has the top connection on the heater matrix connected to the end of the inlet manifold.

The bottom connection on the matrix is connected via a long hose under the inlet manifold to my test take off from the thermostat housing.

At the moment the top hose gets warm first and never seems to get above 30deg C when engine is full temp. The bottom hose from the matrix gets to 20deg C which suggests coolant is flowing from top to bottom and losing its heat to the cabin on the way.

I used to have the bottom matrix connected to a T piece next to the water pump (you can see the two jubilee clips next to each other on the 35mm hose where the T used to be) and with it there, the bottom matrix connection got warm first which is the reverse flow as to what it is now. :?

I've included a photo of a short 180 degree bend hose which seems to go from one outlet to another on the inlet manifold. I've no idea if this is right either but this is where the hose was when I got the engine.

There is no heater valve at the moment as the original had failed and i couldn't find a replacement. I will install one at some point but would like to prove the concept that i can actually get heat inside first before i fit something to control it. I also have a one way valve on its way to me in the post to try... I have a theory that the pump is moving coolant no problem around the engine (temps all good) but may be pushing coolant into each end of the matrix so there is virtually no flow. its an inline valve so easy to try and might, just might lead to the pump pumping only one way through the matrix?...

Photos of someone else's B engine heater connections would be really useful to see or, a bigger scan of flow direction arrows on page 22 in the owners manual :D

thanks again all!


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99L pic 125.jpg
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99L pic 126.jpg
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99L pic 127.jpg
99L pic 127.jpg [ 136.83 KiB | Viewed 263 times ]
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PostPosted: Sun Mar 22, 2020 10:18 am 
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Location: Leeds
Car Model: 900 Turbo 1980 gotta be green
Hi. Tried to enlarge it so you can see the flow direction arrows (which aren't brilliantly clear).

Image


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PostPosted: Sun Mar 22, 2020 10:32 am 
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Car Model: 1972 99L 2 door
Thanks John, that is a little clearer than the low resolution scan i had, its really helpful - thankyou!

I can see an arrow from end of inlet manifold flowing into the heater matrix TOP connection and a return flow from BOTTOM matrix connection to a T piece on the large hose from expansion tank.

That is really interesting as that is how i had it set up originally. I wasn't a million miles off then. :park:

I'm thinking that Im going to remove my test feed from the thermostat housing as that appears that it might be pushing water towards the feed from the inlet manifold (hence no flow)

When my one way valve turns up, i am going to install it in the return line to make sure that water only flows one way when it rejoins the the large pipe connected to the pump cover.

If that doesn't do anything then i am left with nothing other than to fit a min pump somewhere to scavenge some hot water from the circuit and push it through the matrix.

I have been looking at motorbike pumps, parking heater pumps, caravan heater pumps and after run coolant pumps from some cars. All a small 12v pump, can handle hot coolant and with the addition of a speed controller; should be able to replicate the hot/cold control by pumping more or less water...

I am encouraged the end is in sight!

Cheers


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PostPosted: Sun Mar 22, 2020 10:40 am 
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Full Pressure Turbo

Joined: Fri Jun 16, 2006 9:26 pm
Posts: 636
I've had a look at the manual and basically my description above is about right. The are many variations for 1850, B20, H type, single carb, twin carb, fuel injection, but they basically all work the same way.

On the carb version the hot water passes into the inlet manifold from the ports in the cylinder head. If it can't get into the heater because the valve is closed it returns to the inlet side of the pump through the small link hose that you referred to. If the heater valve is open the hot water leaves the inlet manifold via a hose connection to the heater valve. On a B20 the water leaving the heater returns to the water pump inlet via a T connection to the big hose from the header tank to the water pump. 1850 is a bit different but I think connects directly to the water pump cover.

Basically to get a flow you need to connect the heater 'across' the water pump or have the connections either side of the thermostat (which amounts to the same thing as the thermostat is the restiction in the system). If this is not possible I'd suggest you need a small auxilliary pump for the heater circuit, something similar to a pump used for a chargecooler system on a turbo car.


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PostPosted: Sun Mar 22, 2020 10:47 am 
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Car Model: 1972 99L 2 door
yes, you are right about the 1850 engine - when the dead 1850 that came in my car was removed, the heater was plumbed into a connection on the top of the pump. This is why i was unsure of how to connect up the electric pump / matrix circuits.

I am of the opinion i probably need an extra mini pump to help push water through the matrix but i would prefer not to if i can get away with it - more 'things' and more wires.

By reinstating the return line into the flow from the pump like I had it initially, i was getting the bottom matrix hose warm up first which tells me the flow was the wrong way round. I am now thinking if i connect the return line to PRE electric pump, i wonder if it will 'suck' water through the matrix. Well, i say suck but a small enough pressure difference to encourage water to actually flow through it will do me. :D


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PostPosted: Sun Mar 22, 2020 6:25 pm 
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Joined: Sun Apr 16, 2017 7:16 pm
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Location: Leeds
Car Model: 900 Turbo 1980 gotta be green
Here's the schematic for an early 900 with the b-series engine. It may help a bit.

Image


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PostPosted: Sun Mar 22, 2020 8:05 pm 
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Joined: Mon Nov 03, 2014 9:45 pm
Posts: 153
Location: Sandbach, Cheshire
Car Model: 99L,9000,9-5, Rovers & Imp
The original pump operates both the by-pass circuit when the thermostat is closed which also feeds the heater. With the electric pump in the radiator return pipe water won't be circulating around the bypass circuit and neither around the heater.

I would say the 180 by-pass pipe needs to be linked into the radiator hose before the pump ( blocking off the old pump 16mm pipe ) which would resolve the warm up by-pass circuit. Not sure what this would do to the heater feed though.

_________________
John
Sandbach, Cheshire
1973 99 2.0L
1997 9000
2006 9-5 2.3
1957 P4 90
1968 Imp Super
1974 P6 3500


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PostPosted: Sun Mar 22, 2020 8:46 pm 
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Car Model: 1972 99L 2 door
Interesting thoughts here :)

The issue definitely seems to be related to flow and not enough of it... The electric pump only pulses on and off fairly slowly during warm up and progressively longer 'on' pulses until it runs full time when the engine is fully hot.

When it is running full time the matrix does actually heat up. This of course doesn't help cold starts / frosty / damp days.

Interesting point re the 180degree hose. I'm going to try putting it back to how it was with heater return pre pump and see what happens. If it doesn't work, I've got a range of adapters, connectors and pumps saves in my ebay... Between them I'm sure they can plumb some early heat into my heater!


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PostPosted: Thu Mar 26, 2020 4:39 pm 
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Car Model: 1972 99L 2 door
thanks to everyone who posted a reply, I've got good news - it is sorted.

I'm really reall'y chuffed as all it took was understanding the flow (thanks for the diagram) a bit of discussion and a brain wave. Connecting the heater matrix return line to PRE pump is what i have been up to today and the results are a heater that behaves like it should. Heat is felt early on during warm up with coolant in the low 40deg C and when i get to my benchmark 75deg C, the temp of the inlet pipe for the matrix is 59deg C. Before swapping the connections round, this only ever got to 30deg C. I say this is conclusive evidence of flow and at a point the electric pump controller is not running the pump full time.

Couldn't be happier but then i look out of the window and notice it has come just as spring arrived! :roll: :lol:


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99L pic 129.jpg
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99L pic 130.jpg
99L pic 130.jpg [ 100.46 KiB | Viewed 97 times ]
99L pic 131.jpg
99L pic 131.jpg [ 63.41 KiB | Viewed 97 times ]
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PostPosted: Fri Mar 27, 2020 6:30 am 
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Car Model: 1972 99L 2 door
I couldn't resist a test to see how the new heater performed against this mornings frost...

In no time at all it was doing the job which allows me to post this really interesting photo :geek: :lol:


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99L pic 132.jpg
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PostPosted: Fri Mar 27, 2020 8:50 am 
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Location: Mulbarton,Norfolk
Car Model: TTid's only now :-(
Any good?


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PostPosted: Fri Mar 27, 2020 10:45 am 
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Car Model: 1972 99L 2 door
Thankyou, that's really crisp!

My heat situation is all sorted now - I rerouted my pipes yesterday and this morning was able to melt ice off my windscreen no bother at all.

Cheers


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