Does it matter?

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odyssey

Active Member
Posts
364
Location
Derbyshire
which way the coolant flows through the heater matrix? Rave diagrams are conflicting (pages 212, 213) through the metal pipes but I can't see any ref to which is the 'in' and 'out' to the matrix at the firewall.

Recently replaced the blocked radiator on my '93 LSE following top end rebuild and the heater sometimes works and sometimes doesn't.
It will blow hot if the fan is turned on then gradually gets cooler, so the flow seems to be restricted somehow, both the flow and return pipes are hot, engine temp is (finally) stable and correct.

Flushed the matrix both ways repeatedy and the flow seems unrestricted in both directions, some solids come out initially then it runs clear. Following flush it's OK then gradually cools down til no heat at all. I wondered about crossing the pipes over so it runs 'backwards' through the matrix in case there is a large bit of crap/scale in one of the end tanks that is acting like a butterfly valve . . .

The cooling system has been pretty well flushed through following rebuild (and several overheats proior to rad replacement). No antifreeze in yet as I want to sort this before adding it.

Any comments/ideas/suggestions?

TIA Alastair
 
odyssey said:
which way the coolant flows through the heater matrix? Rave diagrams are conflicting (pages 212, 213) through the metal pipes but I can't see any ref to which is the 'in' and 'out' to the matrix at the firewall.

Recently replaced the blocked radiator on my '93 LSE following top end rebuild and the heater sometimes works and sometimes doesn't.
It will blow hot if the fan is turned on then gradually gets cooler, so the flow seems to be restricted somehow, both the flow and return pipes are hot, engine temp is (finally) stable and correct.

Flushed the matrix both ways repeatedy and the flow seems unrestricted in both directions, some solids come out initially then it runs clear. Following flush it's OK then gradually cools down til no heat at all. I wondered about crossing the pipes over so it runs 'backwards' through the matrix in case there is a large bit of crap/scale in one of the end tanks that is acting like a butterfly valve . . .

The cooling system has been pretty well flushed through following rebuild (and several overheats proior to rad replacement). No antifreeze in yet as I want to sort this before adding it.

Any comments/ideas/suggestions?

TIA Alastair
Click to expand...

In my experiace YES it does matter which way its connected as hot water tries to flow a certain way, ive found in the past with other vehicals that when connected wrong the hot water tries to flow threw the matrix in opp direction to the water pump, im not sure with the rangies but in genneral yes it makes a differance.
 
turn um round and see if its better, but have RR pointing up hill or a bad airlock may form in the matrix, i did mine on ramps and all was good. still had to do the usual for getting the air out the system. :)
 
dougdotcom said:
turn um round and see if its better, but have RR pointing up hill or a bad airlock may form in the matrix, i did mine on ramps and all was good. still had to do the usual for getting the air out the system. :)
Click to expand...


Hellooooo, sorry to be a pain buttttttt how do you do it:D what is the usual way you use matey.
 
I think it matters which way the hoses are on , on my old bmw the mechanic wapped them by mistake once and it didnt work.

I have the exact same problem as you in my 1990 RRC, I am still workin on it but have had some improvments by wating until the engine is really really hot then cracking the nut on the fill tower and letting out any trapped air.

Let me know if you find the magic bullet though mate!
 
"on my old bmw the mechanic wapped them by mistake once and it didnt work."

I'm getting to the stage where I feel like I want to wapp it:eek:.

The heating system on the two 6 pot BMs I had (as far as I remember) worked differently in that the controls operated a water valve to allow hot water into the heater, whereas on the RR water flows through it constantly - or at least it's supposed to.
(Rave is unhelpful as the softdash system is different - it has a water valve.)

I don't see that running it in 'reverse' could cause any severe problems, I assume (looking at the various pics of it) that the matrix is a crossflow system with both ports at one end and if it operates like the main rad, it should flow 'down' the way - against the natural convection current, but as there seem to be intermediate pipes between the matrix and firewall connections, it's difficult to see which is the 'in' and which is the 'out'.

I wondered about running the engine for a short time from cold (stat closed) with the 'output' pipe from the manifold disconnected to see what the flow is like, but does the water pump 'suck' coolant through, or is it 'pushed' through the engine block?

I think I'll just swap the pipes over and see . . .

A
 
swapped lol

Not sure on the pump, I wonder if my pump might be tired as the heater is much better over 2000 rpm but goes cold after a while at idle.

The bleeding I did from the fill tower really did help,maybe try that???
 
jt_armstrong said:
There is a sensor attached to the hot (input) just before the matrix.
Click to expand...

Not on the Classic there isn't (unless it's buried away right under the dash), and anyway the few degrees of temperature drop across the matrix isn't going to make a huge difference to anything much. Apart from the temp inside the car if the b****y thing worked!

But thanks for the thought . . .

A
 
Done 20 miles with constant heat!. So it either does matter (and I'd put them back on the wrong way after the rebuild) or there is something in the matrix that's partly blocking it the other way round.

We'll see how long it lasts - I'll give it a couple of days and then put the antifreeze in.

I'd still like to know which of the matrix connections on the firewall is the 'in' one - maybe some kind person could have a look and let me know if it's the higher or the lower one.

Thanks - A
 
let me know how well its works mate, maybe someone has swapped mine over behind the dash and messed it up???

The hoses are on the right side according to the others I have seen on the engine side of the bulkhead but I cant see the side behind the dash.
 
The feed pipe is the one that comes from the waterpump and goes to the right hand (upper) tube from matrix. The return goes to the left hand (lower) tube on the matrix and returns to the thermostat housing. P38 that is.
 
Hmmm - thanks wammers, but I think the P38 is different, looking at page 213 of rave, "From the manifold the coolant is carried
by an external pipe to the heater unit and from the
heater through another external pipe to the pump
inlet."

The diagram sort of confirms this, although the diag on the previous page contradicts itself on the flow arrows . . .

A
 
odyssey said:
Hmmm - thanks wammers, but I think the P38 is different, looking at page 213 of rave, "From the manifold the coolant is carried
by an external pipe to the heater unit and from the
heater through another external pipe to the pump
inlet."

The diagram sort of confirms this, although the diag on the previous page contradicts itself on the flow arrows . . .

A
Click to expand...

Believe me the feed pipe comes from the water pump (pressure side top of engine) to the r/h tube that is the upper tube on matrix. The return goes from the l/h tube or lower one on matrix back to the thermostat housing then back into water pump suction side. My version of RAVE shows upto 1998 and 1999 on. On both versions the feed and outlet and the circulation are the same. Some other things differ but the heater circuit is basically the same.
 
Wammers - I fear we may be talking at cross purposes, it's a '93 4.2 classic LSE, non serpentine, and my version of Rave (which has the details of the 95 softdash classic - no P38s) shows the flow from the manifold to the pump, with the accompanying words:-

"When the engine is started from cold the thermostat prevents any coolant circulation through the radiator by closing off the top hose. During the engine warm up period, the water pump, pumps coolant around the
cylinders to the rear of the cylinder block along the main galleries in both cylinder banks. At the rear of the cylinder block the coolant rises through a large port in each cylinder head/block joint face, and then flows forward to connect with ports at the front of the inlet manifold. From the manifold the coolant is carried by an external pipe to the heater unit and from the
heater through another external pipe to the pump inlet."

I know the p38 has a much more complex hevac system and there is a valve in the heater circuit somewhere.

But thanks for the comments :)

A
 
odyssey said:
Wammers - I fear we may be talking at cross purposes, it's a '93 4.2 classic LSE, non serpentine, and my version of Rave (which has the details of the 95 softdash classic - no P38s) shows the flow from the manifold to the pump, with the accompanying words:-

"When the engine is started from cold the thermostat prevents any coolant circulation through the radiator by closing off the top hose. During the engine warm up period, the water pump, pumps coolant around the
cylinders to the rear of the cylinder block along the main galleries in both cylinder banks. At the rear of the cylinder block the coolant rises through a large port in each cylinder head/block joint face, and then flows forward to connect with ports at the front of the inlet manifold. From the manifold the coolant is carried by an external pipe to the heater unit and from the
heater through another external pipe to the pump inlet."

I know the p38 has a much more complex hevac system and there is a valve in the heater circuit somewhere.

But thanks for the comments :)

A
Click to expand...

Sorry, yes it would seem so. :):):)
 
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