No hot air from heater, engine overheating, water full - air lock? ('96 Punto)

oq4v3ht0u76kf2

Hi there,

Having a problem for the past week or so with my 1996 Punto. Essentially, no hot air will come from the heater (obviously have it set to hot) and the engine just heats steadily whilst I drive until the needle hits the red - and sometimes beyond.

I get about 20 minutes urban driving (max speed 60kph, lots of sitting at traffic lights) before the needle is in or above the red and I need to pull over, give it 5 minutes to cool a bit, then carry on. When I do pull over there is a lot of pressure in the cooling system (i.e. if I loosen the cap lightly there is water / steam being forced out) but the radiator fan has not kicked in.

I've done a bit of Googling and the most likely causes I've found seem to be:

1. Best Case: air-lock in the cooling system
2. Worst Case: head gasket gone

Apparently the quickest way to diagnose the head gasket being gone is to check for "mayo" around the oil whilst the best way to sort the air-lock is to bleed the system - does anyone know of a quick guide to doing this?

Any other suggestions?

Cheers,
Rob

Joe 90

Thermostat?

ottostreet

Head gasket.

homer90

Have a look under the oil filler cap for oil residue.

Open to correction on this, but when hot the cooling system is pressurised , so when you opened the the cooling cap it should release trapped air.

ltdslipdiff

The cardboard head gasket in the Punto's is pretty weak. Could have frozen causing blockage -> overheating -> head gasket......

BrianD3

Sounds more like a water pump than a head gasket to me. If the HG was gone and letting hot gases into the coolant the heater should be hot and the rad fan on constantly. I'd say an airlock is unlikely unless there has been work done on the cooling system recently.

If the thermostat was stuck closed the heater should get hot while the rad stays cold.

If the gauge were faulty you probably wouldn't be getting a cold heater while having hot coolant in the expansion tank.

Timmaay

Reuben Wooden Puff wrote: »

Having a problem for the past week or so

And your still driving it??? An overheating engine will seize sooner rather then later, or at the vary least the head will warp, in any case the engine will be wrecked!

MarkoC

More likely temp sensor in radiator which gives signal to the fan is gone.

BrianD3

MarkoC wrote: »

More likely temp sensor in radiator which gives signal to the fan is gone.

In that case he should still have a hot heater.

Howver maybe he has more than one problem.

oq4v3ht0u76kf2

Cheers for the replies gents, okay, I followed the following steps to try and cure any potential air-lock:

1. Unscrewed screws on hose going into the back of the engine (bulkhead?) and at the top left of the radiator (as you stand looking into the windscreen)

2. Kept filling the coolant tank until liquid was pissing out of the back screw

3. Tightened the back screw

4. Continued filling the coolant tank until liquid was pissing out of the radiator screw

5. Tightened the radiator screw

6. Filled the coolant tank to the maximum line

Then I started the car and ran it for a few minutes, when the temp needle hit the mid-way mark the radiator kicked in for a second or two then it stopped. At this point I noticed that there was steam coming out of a point at the top right of the radiator. I took a picture but you can't see the steam too well 'cos of the camera flash:



All the while I had the heater on in the car but it never got warm. It wasn't as cold as the air outside but there was definitely no warmth in it.

So, it seems as if there's a bit of leaking going on inside the radiator itself - does that even make sense / sound plausible? You can probably tell I'm not the most knowledgable when it comes to vehickles!

Any suggestions welcome!

Stheno

I don't know much about cars, but having driven old cars for pretty much all my life, twice I've come across problems with no hot air in the heaters, and the engine overheating.

Once the engine blew on the motorway, (Opel Vectra), the other time was with my Fiat Punto where the head gasket blew.

I'd suggest you get that car to a garage asap, rather than hanging about an internet forum. You don't want either of the above to happen.

Mozoltov!

Check the oil cap for a milky sort of residue. If it's there, don't drive the car.

How would you be at tackling the head of the engine yourself to see if the head is gone?

oq4v3ht0u76kf2

I looked for the "mayo" like substance around the oil cap but no sign of it. I know the head gasket is a common enough problem with these models but most people seem to say if there's no milky/mayo-like residue around the oil then it's unlikely it's the HG... though I could be wrong?

Any way to tell conclusively without going most of the way to replacing it anyway?

LookBehindYou

When your heater in the car is COLD when the car is warmed up, its an indication that the head gasket is gone.
A warmed engine should have hot water in the TOP and BOTTOM of radiator.
If the head gasket is blown, there is a chance that the alloy head is warped, but the head can be skimmed and use an oversize head gasket.
Its not a big job to do on a punto, But you will have to get the head skimmed in an engineering shop. There is a good place for that in Baldoyle, in the ind est behind Dennis Mahonys.

LookBehindYou

Reuben Wooden Puff wrote: »

I looked for the "mayo" like substance around the oil cap but no sign of it. I know the head gasket is a common enough problem with these models but most people seem to say if there's no milky/mayo-like residue around the oil then it's unlikely it's the HG... though I could be wrong?

Any way to tell conclusively without going most of the way to replacing it anyway?

A head gasket can be gone in different ways.
1 : Blown where it allows water to mix with oil.
2 : where it blows pressure in to the oil.
3 : where it blows pressure in to the water.

No : 3 is the most likely case.

oq4v3ht0u76kf2

Ah balls, seems like it could well be the HG then... don't know if my very limited skills are up to it though I might give it a shot. If I was to go to a mechanic with it, any idea what sort of wedge I'd be looking at forking out?

Stheno

Mightn't be as bad as you think Rob B, my gasket blew the week before Christmas and my local (trusted) mechanic was working over Christmas and it cost 400 (3 years ago)

Where are you located? I can recommend a good mechanic who won't rip you off in Swords if you are about that area?

oq4v3ht0u76kf2

Yeah, I live in D13 and actually work in Swords - any recommendations definitely appreciated!

Stheno

Sent you a pm, not sure about the rules here for recomendations!

barochoc

Sounds like thermostat or water pump. The head might not be gone yet.

Check inside the coolant/radiator cap during daylight to see if there's a rainbow type slick on the top. If you have this means oil is getting in to the coolant & the head is gone. The milky/mayonaise type gear on the oil cap is normally only evident after driving with head gone for a long time.

Check the hose on both sides of the rad. Normally one top & one bottom to see if they're both hot when the gauge says the engine is hot. If one of them is cool (normally the bottom one) or not very hot it generally means the water pump is not doing it's job as they should both be hot.

The fan should be coming on once you pass the normal operating temperature. If it's creeping up to the red & still not coming on the thermostat must be gone or possibly a relay for the fan. It's sometime easy to just connect the fans contacts to another 12v car battery or directly to your own to see if the fans motor is working right.

It's a process of elimination. Good luck