Technical strange overheating problem

[Mar4ix]

So, .. punto 55s, 1.2 engine, 8v. 1996.
Changed a while ago heater matrix, waterpump, temp sensors (both), thermostat and coolant.

In city driving, temp gauge rises up to 3/4 of heating scale.

When on motorway, driving at around 100 km/h (5th gear and revs at round 3 k) for 5 miles , temperature goauge hits red line. when put in neutral, gauge kind jump even higher, but when i rev up to 4 -5 k(in neutral) temp goes down to half last quarter, then again , i am driving for a mile or 2, get temperature up to red line, put in neutral, for few hundred meters, then rev again, temp falls, and driving couple miles further.

Bit annoying.

So far checked number times coolant level, no changes at all, tried bleed system, but from pipe at the back of engine on heater matrix pipe goes coolant out only, no air at all.
No any pressure in coolant pipes.


In garage, where i have to pay, they diagnose headgasket leaking, in garage where i did for free (friend of friend garage), they couldn't diagnose headgasket leak.

Any ideas where to look at?

Just have left one idea, thermostat, but i got it new, from ebay, as a genuine fiat thermostat... , might have to remove it and see how it goin to go then. i have no idea where to look at else, to solve this problem.

Maybe headgasket, but i have no any symptoms of it (excluding overheating).

thanks

 

[dumbledore]

Temperature sensor may be lying and shows erratic temperatures. Check to see if the radiator fan is coming on when the temperature goes high above 1/2. Also check to see if the radiator goes hot too when the engine temperature shows hot.

 

[Mar4ix]

Temperature sensor may be lying and shows erratic temperatures. Check to see if the radiator fan is coming on when the temperature goes high above 1/2. Also check to see if the radiator goes hot too when the engine temperature shows hot.

thanks for replay, forgot to mention, that when geting to temp red line, logically, i am turning heating up on full blast, but there is barely warm air goin, when reving up, temperature drops, and hot air start go from wents. other day, when was changing coolant, were heating up car, and rad fan kicks in, now i didnt check is rad fan on when hot, but i know pipes to radiator just pretty warm, but not hot.

 

[fingers99]

Check stat, check fan for operation.

Only sure test for HG is compression test -- everything else is an educated guess.

 

[s and b]

without denigrading the seller of your thermostat how do you know its an original and not a copy?
also thermostats can and will go faulty new or used
you dont mention checking the radiator for blockages either,remember at this age some dummy might have used an elixior of fools oil to fix a leak prior to you owning the voiture

 

[Most Easterly Pandas]

Could also be worth considering the pump, might not be flowing the coolant around very well, and only flowing fast enough when the revs are high, like you've been saying is the case.

 

[Mar4ix]

Check stat, check fan for operation.

Only sure test for HG is compression test -- everything else is an educated guess.

will check stat.

What pressure shall be on healthy cylinder, and what pressure would show faulty hg ?

 

[thelad]

If the heaters are going cold its air in the pipes or blockage/restriction.

 

[Mar4ix]

If the heaters are going cold its air in the pipes or blockage/restriction.

were thinking as well about ir, but pipes goin hot also, so it more likely air lock.

To do proper cooling system check , refill coolant, do i have to rise up front. I know some bmw need to do that , wonder would punto need to do this, , to make air escape off system ?

 

[Most Easterly Pandas]

were thinking as well about ir, but pipes goin hot also, so it more likely air lock.

To do proper cooling system check , refill coolant, do i have to rise up front. I know some bmw need to do that , wonder would punto need to do this, , to make air escape off system ?

If its a radiator mounted expansions tank then there will be a bleed point in on of the top corners of the radiator, and probably one near the bulkhead where the pipes go to the heater matrix

 

[fingers99]

will check stat.

What pressure shall be on healthy cylinder, and what pressure would show faulty hg ?

Best that you don't know (because it's easy to subconsciously juggle the results a little!) -- just post here and we'll explain/judge/prevaricate.

 

[Mar4ix]

Best that you don't know (because it's easy to subconsciously juggle the results a little!) -- just post here and we'll explain/judge/prevaricate.

Ok, will do pressure test tomorrow... if not goin rain much.... i have pressure tester, just need somehow switch off fuel pump, is there fuse for fuel pump?

if there will be fuel goin in, and ill disconnect ignition, than results will be incorrect.

 

[Ziggy122]

do mk1 use a crank sensor for the ignition? like the mk2
If so - disconnect that, it'll stop the injectors and the sparkies
so the fuel pump wont need to work - but the engine wont start tho

Ziggy

 

[thelad]

Yes the TDC plug at the rocker cover, disconnect it.

 

[fingers99]

Yep, that'sw the easy way. Warm the engine up beforehand, and do the tests with throttle fully open.

 

[Mar4ix]

So folks, sorry, couldnt do test yestarday as promise, i was after nightshift, simply didnt wan gou outside, so did today.
Engine testing with tool like that - http://www.ebay.ie/itm/290377167798?ru=http%3A%2F%2Fwww.ebay.ie%3A80%2Fsch%2Fi.html%3F_from%3DR40%26_trksid%3Dm570%26_nkw%3D290377167798%26_fvi%3D1&_rdc=1
and went with results like that.:

third cylinder (from timing belt side) i was testing twice, as there was no room to tightening up that bloody thing, and second time manage get more tight.


Any suggestions, and comments about pressure ?

I have no idea about, how good or bad that pressure is.

First three readings with throttle closed, and under line with throttle fully open.

 

[s and b]

ive inverted your picture to make it more readable


what action did you do in relation to post 5/?

 

[Mar4ix]

ive inverted your picture to make it more readable


what action did you do in relation to post 5/?

Thanks for re-doing my picture

Nothing yet with thermostat. will do tomorrow.

 

[fingers99]

To my mind the HG is fine, with the proviso that the readings from #3 are low because of the issues you indicated.

 

[Mar4ix]

So, today got her till temp red line, even till middle of red line on temp scale. Checked pipes, strange, ... top pipe warm, botom barely worm, in same time engine on red line, and coolant on proper level on rad..... any idea, what could cause this ?