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Coolant bleeding and stone cold heater?


Rich H

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Evening all,

Got my car running but seem to be having issues with bleeding the coolant system.

The dash gauge only got up to 60* but the oil temp reached 80* odd.

Got the back in the air a bit with the engine running and got a bit of air out of it but the heater is still stone cold.

Also the level sender is goosed, it's not attached to anything inside the case, there is just some brown squashy stuff with broken wires in. Is there an easy way to frig it so it reports 'full' until I can find a replacement? No ECL though?

Is there a knack to bleeding or is there a heater bleed point?

Any other thoughts?

Ta

Rich

Edited by Rich H

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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Careful with the dash gauge reading for water T° because there are 2 sensors: one for the ECU and one for the gauge. I have found out that the its a common fault for the latter to go duff and give false info to the dash gauge. I've just received a new T° gauge sensor to rectify this problem on my S4s because the gauge never show T° beyond 70 and sits at 50° most of the time. It's far better to read the coolant T° from the ECU via Freescan to get an accurate value.

1980 Peugeot 504 Coupé V6Ti

2000 Peugeot 406 Coupé V6SE

1996 Lotus Esprit S4s

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There should be an air bleed valve at the top of the radiator, passenger side, though I doubt air is causing your problem. Have thoroughbred flushed the system? which includes removing the "header" tank and flushing it.

Life is like a sewer, what you get out of it, depends on what you put into it. (Tom Leahrer)

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Rich,

If you have air in the cooling system, it will run hot and usually very quickly so as Herve` mentioned above, don't rely on the temp gauge if you're not sure it's working.

If you can't check it with Freescan, an infrared temp gun aimed at the thermostat housing will get you a close reading. Once you're sure the coolant system is full and cooling properly, then tackle the heater problem. That could be a clogged heater core or valve not opening among other things...

Edited by lotus4s

1995 S4s

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OK thanks.

I have a VDO sender from one of my old Porsches I'll try sub that in on the off chance it's the same and drop it in some hot water see if the gauge works.

The rad is getting hot, the rad is bled and the pipework from the t-stat is v.hot to touch (Not burning hot but still v.hot) as I'd expect.

Turning the temp knob is very stiff too, so I suspect it might be control valve related.

Need to sort freescan out, going to investigate a DIY version as I have all the requisite bits I think to build a serial cable version.

Thanks

Rich

Been looking at the parts diagrams: Is the heater valve on a 94 S4 in the passenger footwell?

I want to give it a good exercizing and lube with WD40. If necesary I'll pull it out and give it a good cleaning out.

Thanks

Rich

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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There is no heater valve as such. The heater matrix is permanently in circuit and its the air that is either diverted through it or past it.

The matrixcould be blocked, it's easy to check as ifyou jack the front of the car you can see 2 small (quick guess about 20mm diameter) rubber elbows coming from the front box section of the chassis then going straight upwards. Ones the heater feed, the other is the return.

Have a feel of both and see what you've got.

If it's blocked you can drop off both pipes and flush it with a hose pipe to ensure good flow. Back flush is best to remove the crud I'd say.

Oh, one thing to remember is only the screen and footwell vents blow hot. Your dash front ones are always cold iirc

Chunky Lover

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There's no need to jack the rear of the car up, an S4 bleeds satisfactorily when on a level surface. One simple thing to check is whether your vacuum pump is running continuously (usually indicating a vacuum leak somewhere) or not running at all as either will result in the vacuum operated flaps not allowing heat through.

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Vac pump runs initially for about 30 secs then runs for a couple of secs every minute or so unless a heater control is operated I assume I have a small leak but you can hear the flaps moving about.

I'll try the flush trick (I'll hide the hose - we still have a hosepipe ban!!)

Cheers

Rich

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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I'll have to have a look at the diagram when I get in later. Thought it was only the V8s that had a water control valve. Maybe they introduced it in the later 4cyls as well.

Watch your water pressure isn't too high when attempting a flush, wouldn't want you busting your matrix. Just take it easy I guess..

Edited by Simon350S

Chunky Lover

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The water in the reservoir is definately moving adn the rad is hot - would get round the system without it? :question:

I'll look in the pax footwell for this valve and see if I can find it and free it off, then I'll try back flushing.

Cheers

Rich

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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Just for completeness, as there is nothing worse than finding a similar problem with no solution!

Gauge worked fine - I was looking at the wrong gauge... :censored:

Heater was the temeprature hot/cold control cable had come adrift and wasn't moving correctly.

Pulled out the pocket under the heater controls, got the front heater control panel off and undid the nut on the rotary control

I could then get to the cable and sleeve, the outer sleve had come undone and the whole lot was moving.

Pulled the outer back into place and re-clamped it - beware all the fittings are imperial!!

Both working just fine now!

The bleeding problem was a cracked expansion tank sucking in air instead of taking coolant from the reservoir -£8 tank from e-bay fixed it!

Thanks

Rich

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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