piddy
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| posted on 12/8/07 at 05:46 PM |
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overheating
Anyone got an answer to the below e mail please?
Hi Martin,
The ignomy of it ! being delivered home on the back of a breakdown truck.
I'm not sure just what's wrong yet. Driving home from Helmingham last week
the temp gauge went right off the scale, but checking the radiator showed it
to be hot, but not overly so. One thing I did find when checking round was
that the electric fan was quite noisy. I fitted a new (scrap yard) fan this
week, and at the same time removed the thermostat, firstly to eliminate a
sticking therm. and secondly to give a better water flow round the cooling
system.
Everything went back together ok, fan cutting in and out correctly, and
cooling system filled with a 50/50 mix to raise the boiling point. After
about 5 miles this morning I suffered a sudden misfire, but only when trying
to accelerate. I nursed the car along on a trailing/or light throttle for
about half a mile, then it suddenly picked up and drove normally!
A few miles later the temp gauge headed for space again, going off the
scale, through the red marker, and out of sight ! I decided it would be
like last week - a high reading, but holding normal temperatures, but a few
miles later I saw steam coming through the bonnet vents, so I pulled off the
road.
Lifting the bonnet revealed coolant everywhere, especially over the
distributor area, so that explained the misfire. A closer look showed the
top hose to be nearly off the pipe at the radiator end. I immediately
opened the header tank cap, very slowly of course, but there was no great
escape of pressure, in fact very little at all.
I slackened, moved and re-secured the top hose, checked that I still had
coolant in the header tank, then turned round and headed for home. About
half a mile later steam was pouring through the bonnet vents again, so I
switched off, coasted to the side of the road, and lifted the bonnet
(again). Once more the top hose was almost off the rad pipe, but the header
tank was still full.
At this point I invoked my AA membership and rang for a lift home (not bad
really 1 1/2 hours from phone call to pick up). At the moment I have done
nothing more than drive the car into the garage. Bernie thought it was
bonus day and give me some more decorating to do, even though I spent all
day yesterday laying laminate floors !! I will start an investigation of the
car tomorrow after work.
Syptoms now are: very high pressure in the radiator, but normal pressure in
the (remote) header tank.
oil level has stayed the same, so the water
isn't going there
heater is barely warm (very unusual for this
car) so points to air in the system where there should be water
while I had the the thermostat housing off I
turned the water pump by hand, easily managing to get water out of the
bottom hose
the configuration of the cooling system
hasn't changed from when I completed it 8 or 9 months ago
As yet I haven't done a compression test - that will be tomorrow.
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rusty nuts
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| posted on 12/8/07 at 06:14 PM |
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Could be head gasket failure , check for bubbles in the header tank or better still use a block tester. Would also explain the misfire if water was
getting into the cylinder(s) . Water may not be getting into the sump , just going out of the exhaust . Would pressurise the cooling system as well .
Heater could depend on the stat directing coolant through heater.
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dr-fastlane
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| posted on 12/8/07 at 06:47 PM |
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Check the cap from the header tank. When my car overheated it appeared to be the filler cap that had a worn O-ring (VW header tank).
------------------------------
I have not failed once. I have successfully found ways that will not work!
https://www.motor-forum.nl/threads/hardtail-dragstyle-project.343482/
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Fatboy Dave
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| posted on 12/8/07 at 07:00 PM |
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Sounds very much like an airlock?
Dave
Stop the planet, I want to get off
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RazMan
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| posted on 12/8/07 at 09:37 PM |
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My money is on an airlock too - maybe you lost some coolant through the dodgy rad hose and sucked a load of air in. Try bleeding the heater matrix and
any other high points with the rad cap off.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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FazerBob
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| posted on 24/8/07 at 08:35 PM |
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Overheating
Mine is the car Piddy mentioned at the start of this post, so now I will try and bring you up to date.
Compression test showed very low reading on No3, and slightly low on No4. Head removed, and as expected gasket blown between 3&4.
Everything cleaned up and re-assembled with new head and manifold gaskets. Compression test now gives 160+ on all cylinders.
Ran the car down the road yesterday, cooling system filled with plain water, after forward and back flushing of the complete system, then filling with
engine degreaser and run for a further 10 mins.
Car ran like a complete pig! coughing and spluttering, and struggling to idle. Traced running fault to an air leak at the inlet manifold.
On returning home I left the car idling (by turning up the throttle screw by 2 turns!) the temp gauge stayed more or less in the centre of normal,
electric fan cut in and out ok, and all seemed well. I should mention that I was still running without a thermostat.
Found time to work on the car today, intention being to fit another new inlet manifold gasket, new thermostat and replace the plain water with coolant
mix.
Carried out the above jobs, then ran the car down the road again - still running like a pig, and overheating!! Checking showed the inlet manifold
still leaking, could possibly be warped with all the excess heat. Cooling system playing silly buggers again, top hose cold, everywhere else red hot.
This points to a jammed thermostat yes? Kept the car idling until eventually the thermostat opened and the top hose heated up.
I now have both rad hoses hot, but rad itself cold. Switched off and carefully removed the (plain) rad cap, and no water in rad, plenty of water in
the header tank (which is higher than the rad). Removing the header tank cap lets the water 'gurgle'it's way down - presumably to
the radiator. Watching the header tank water slowly dropping I noticed a small puddle of oil in it. That's enough for today, plus the car is a
bit hot now.
Tomorrow I intend to start with another compression test (just in case) then I'll remove the thermostat, fill the system, run the engine, and
see what that brings.
Bob
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rusty nuts
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| posted on 24/8/07 at 09:12 PM |
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What engine do you have? It may be possible to remove the temperature sender when filling cooling system to act as a bleed point? Perhaps drill a
small hole in the flange of the thermostat to allow air past? When filling my x flow from scratch I take the thermostat out and lift the top hose and
t/stat housing while filling until water runs out of t/stat seat , then refit stat and housing.
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FazerBob
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| posted on 24/8/07 at 10:01 PM |
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Engine is a 1.8 pinto
Bob
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Peteff
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| posted on 24/8/07 at 10:50 PM |
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Which way round have you got the thermostat? It's possible to get it the wrong way round so the stat part is to the radiator instead of to the
block. You can remove the blank on the housing to release air as you fill the system.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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FazerBob
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| posted on 25/8/07 at 10:03 PM |
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I started today with a compression test. No 4 gave a reading of 145, all the other cyls reading 160 ish. Not perfect, but good enough for an old
engine. I removed the thermostat (which was the correct way round Pete) then slowly filled the system. Following the advice on this post I checked
carefully for signs of an air-lock, and hopefully found the culprit.
The header tank cap is some 2" above the top of the radiator, but when I had coolant to the top of the header tank (with the rad cap still off)
there was no sign of water in the rad, when of course it should have been overflowing - so I have an air-lock, but where?
After contemplating the situation, with a cup of tea, I decided to try a high tech remedy and blew into the top of the header tank (good job
I've got a big mouth). With much gurgling from the top end of the engine, the coolant in the header tank went down, and the level in the rad
came up. I stopped blowing when the rad was just about to overflow, re-fitted the rad cap, made sure the header tank was half full, then went for a
short run of about 3- 4 miles. During the run the temp gauge went almost to the red a couple of times, but more often stayed at about half way, or
just above. Certainly better than it had been. On returning I left the car idling for about 15 mins and found the fan was cutting in at about 3/4 on
the gauge and taking the temp down to below half.
The header tank is now full to the brim, but the engine is of course very hot. After switching off I could hear the sound of escaping air, which I
traced to the (plain) rad cap. What are the consequences of this? my idea when I built this system was to have the rad fully sealed, with the
overflow pipe connected to the top of the header tank. I'm nearly there I think, but how vital is it to completely seal the rad cap? is the
fact that it is venting 2" below the highest point of the system helping to cause the air-lock? also I am now running the car without a
thermostat, there seems to be mixed feelings about this. I have done it before, but not with a Pinto engine, so is it good or bad? Comments
please.............
[Edited on 25/8/07 by FazerBob]
Bob
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piddy
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| posted on 26/8/07 at 08:03 PM |
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Hi. Bob.
Good to hear that your getting there.
I always ran my Pinto with a thermostat,but plenty of people don't.
Just takes the engine longer to heat up which ins't that much of a problem with a car used mainly in the summer.
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Uphill Racer
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| posted on 27/8/07 at 09:05 PM |
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If you want to run without a thermostat, you need to fit a restrictor on the outlet of the head so as to keep a higher pressure in the head. That
stops localised boiling normally around the exhuast valves.
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FazerBob
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| posted on 5/9/07 at 06:50 PM |
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Latest update. Ran the car yesterday, without thermostat, bit slow to warm up, but not too bad. After warm up car ran well but any heavy use of the
throttle pedal sent the temp gauge needle heading upwards to the red. Backing off and driving gently (strange concept!) let the needle return to
about the half way position.
I drove about 15-20 miles then stopped at a friend's garage, with needle well into the red sector. I sat with the car idling and within about
15 secs the needle had dropped to half way.
Next job was to do another run and stop every time the needle went off the top of the gauge, quickly lifting the bonnet, and taking readings with an
IR temp reader. This showed that the true temp at the thermostat housing was 81 deg, and 79 at the temp sender unit. Top of rad was 80 deg, bottom
of rad 55 deg.
All this means that the new head gasket has cured the original problem of lots of steam, and top hose almost being forced off it's stub. The
very high readings from the temp gauge are most likely being caused by an electrical fault, or knackered gauge.
Usual culprit for faulty gauge readings is the voltage stabiliser, so this was changed for the one on my spare dash. A 10 mile run today shows
exactly the same symptoms, so more investigation required.
The main thing is that now I know the car isn't actually overheating I can stop worrying about the engine 'letting go' and
concentrate on finding the fault. Any advice welcomed.
[Edited on 5/9/07 by FazerBob]
Bob
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RazMan
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| posted on 5/9/07 at 07:21 PM |
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Are you sure that the water pump is ok? It sounds as though you need more flow.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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saigonij
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| posted on 5/9/07 at 07:24 PM |
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re - gauge reading wrong...
what was the engine out of originally? the temp sender units for the gauge are all different for capri / sierra/granada etc... they are designed for
each dash...
this caught me out once when fitting a capri with a sierra engine...
what gauge do you have? what sender is it designed for?
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FazerBob
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| posted on 5/9/07 at 07:37 PM |
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I fitted a new water pump about 6 months ago. I still took it out to check though. I have had water pump vanes disintegrate in the past.
The engine was out of a 1.8 Sierra, but when I built the new dash from Capri parts I changed the temp sender to match the gauge.
Bob
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RazMan
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| posted on 5/9/07 at 07:49 PM |
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It does look suspicious though - the temps you are reading with the IR meter would normally be 15-20 degrees higher for a 'red' gauge
reading.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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