No hot water going into heater

Post by **KirstMin** » Tue Sep 01, 2009 4:41 pm

Hi All,

Finally got the moggie back on the road after 7 months, passed MOT first time

We did a 100 mile drive in it this weekend and I noticed that the heater isn't blowing hot air. The heater itself is blowing fine but a quick feel of the pipe coming into the heater revealed it was cool as opposed to hot so no hot water appears to be passing through it.

Could 7 months layoff have done something? Any ideas what the issue might be?

For info (in case it’s needed): the car is not overheating, it reaches the thermometer temp and then stays there – I have a temp gauge.

Thanks

Kirsten

Post by **Peetee** » Tue Sep 01, 2009 4:51 pm

Probably an air lock. If you have any air in the system or a slight leak that could let a quantity of air get in over time then it could easily make it's way into the heater routing and stay there. If enough gets in it will present too much of a head of pressure for water to push it out of the way and that part of the system will not flow.
It's a simple solution though. Remove both heater pipes at the engine end and top up one till it comes out the other. if you see any sign of dirty water though you'd be wise to keep the hose running and give it a good flush through from each pipe in turn.

Post by **KirstMin** » Tue Sep 01, 2009 5:02 pm

Thanks Peetee, I'll try that and report back.

Kirsten

Post by **PSL184** » Tue Sep 01, 2009 5:35 pm

Heater tap open ?

Post by **KirstMin** » Tue Sep 01, 2009 6:06 pm

PSL184 wrote:Heater tap open ?

Thats the pull switch to the left and down from the steering wheel? This is in the off position (pushed in) and the cable in the engine compartment appears to return when if I pull it open and push it back... not that this means it's working, just an observation

Post by **MarkyB** » Tue Sep 01, 2009 6:11 pm

Have a look under the bonnet at the back/top of the engine.
If there is a brass device with a round part on top turn the round bit anti-clockwise.
If there is a device with a lever on it and maybe a cable going to it, then move the lever away from the body of the device.
Hot water should now flow through the heater.
If not refer to Peetees answer.

Post by **PSL184** » Tue Sep 01, 2009 6:21 pm

KirstMin wrote:
PSL184 wrote:Heater tap open ?
Thats the pull switch to the left and down from the steering wheel? This is in the off position (pushed in) and the cable in the engine compartment appears to return when if I pull it open and push it back... not that this means it's working, just an observation

Yes, thats the one - Knob pulled out should mean heater is on ie water is flowing through the matrix - Although most likely is an air lock as suggested above esp if you have filled the radiator with the heater tap closed at some time....

Post by **MarkyB** » Tue Sep 01, 2009 8:11 pm

Eh Ehhh!
Knob pushed in is heater on. Out is off. Unless the cable has been fitted from the wrong side.
It tells you on the knob how it works (which is further forward than any other hand operated control).
If that's what's fitted you may need to squat down before you get in and look on the bottommost edge of the dash to even see it.
The under bonnet method lets you know what type of control is fitted.
If it's a brass tap then pass on the squatting part, there's nothing to see.

Post by **ssnjimb** » Tue Sep 01, 2009 8:53 pm

When water failed to go into the heater in my car it turned out to be a water pump that had no impeller left It had simply rusted away.

Upon fitting a new water pump the heater works well.

James

Post by **mike.perry** » Tue Sep 01, 2009 9:12 pm

To clear up the heater control saga there are two types of heater control. The earlier cars and 1275 Midget engines have a brass tap at the back of the engine cylinder head near to the battery. This tap is usually fairly reliable.
The 1098 Minor should have a tap in the same place operated from a push pull knob below the drivers glove box. These controls are not quite so reliable. If you have the later control get someone to push the knob in or out and check that the tap on the engine is opening and closing correctly. The knob is labelled which way is open or closed

Post by **bmcecosse** » Tue Sep 01, 2009 10:09 pm

Never ever known an 'air lock' in the heater circuit! Closed tap/kinked water feed hose/failed water pump - YES. Air lock - highly unlikely!

Post by **Kevin** » Tue Sep 01, 2009 10:55 pm

Kirsten if I remember correctly dont you run a 1275 with a heated inlet manifold, is the water getting past the manifold as it does sound like an air lock.

Post by **bmcecosse** » Tue Sep 01, 2009 11:00 pm

Is the heater piped in at all ?? I've seen some crazy pipework - where the heater ended up in a dead end circuit, with no flow possible !

Post by **KirstMin** » Wed Sep 02, 2009 2:25 pm

Kevin wrote:Kirsten if I remember correctly dont you run a 1275 with a heated inlet manifold, is the water getting past the manifold as it does sound like an air lock.

Hi Kevin, bmc et al. Thanks for the replies and comments / suggestions.

I do have a 1275 with water heated inlet valve but this is not plumbed in:

I have the original 1098 lever device which when pushed in used to mean hot water coming though the heater and hot air coming out of the heater when the heater was turned on.

But since I got the car back on the road hot water doesn't come through the pipe to the heater - it remains cold. This issue appears to have been caused by 7 months without use.

I'm going to have a look again tonight to see if it is an airlock.

Wouldn't a brokenwater pump also give me other issues such as overheating? As mentioned, the temperature rises from cold start right up to the exact temperature of the thermometer (88 degrees) and then stays there.

Thanks all

Kirsten

Post by **bmcecosse** » Wed Sep 02, 2009 2:29 pm

Can only just see the heater valve - but it all does seem to be plumbed in correctly. The valve may be stuck - try it both full in and full out - and look inside the car at the heater , to see if the pipes have 'kinked over' where they go into the heater matrix.

Post by **KirstMin** » Wed Sep 02, 2009 2:40 pm

bmcecosse wrote:Can only just see the heater valve - but it all does seem to be plumbed in correctly. The valve may be stuck - try it both full in and full out - and look inside the car at the heater , to see if the pipes have 'kinked over' where they go into the heater matrix.

Hiya, pipes are not kinked - I checked that - and I have also tried pulling the valve and allowing it to release back - which it does.

The heater did work 7 months ago and I didn't touch the car in that time so will try the air lock issue tonight.

Also, am I right in thinking that I would have overheating issues if the water pump was broken? It's definitely not overheating. Also, the water pump has only done 2000 miles over 3 years.

Post by **Peetee** » Wed Sep 02, 2009 5:45 pm

To see if the water pump is working start the engine then carefully open the rad cap. If there are any impurities in the water you should see them flowing past. A torch can help here. If not, try tipping a very small amount of talcuum powder in and watch it sink.

Post by **bmcecosse** » Wed Sep 02, 2009 7:16 pm

The heater matrix may be blocked with silt. Take the pipes off in the engine bay - and flush through with garden hose.

Post by **Kevin** » Wed Sep 02, 2009 8:23 pm

Can only just see the heater valve

Wher is the picture of that, as I cant see one.

Post by **bmcecosse** » Wed Sep 02, 2009 8:38 pm

Top corner of the picture of the engine bay - Hmmm - it just says 'image' now !