high temp maverick

[rusty1]

Can anyone help? Recently bought a 1997 lwb Ford Maverick 2.4 petrol for towing a caravan, i drove the car 300 miles home and it never missed a beat even when sat in rush hour traffic for two hours. Around 40 miles from home on a steep incline the temperature gauge rose well over 3/4 but seemed to drop on the other side. Ran it for a month or so and temp stayed at around halfway when solo. Took the caravan for a run to see how it towed and temp went to well over 3/4 everytime I hit any incline. I'd booked break in the lakes so i had to risk it as only 40 minutes away and the temp sat at 3/4 when towing and went up to just below red when under load. This made me very nervous so heaters were on full. I thought fan must be working as when i pulled over temp would drop with engine running. When i got home i changed thermostat. The one that was fitted was 79.5 degrees but the one supplied was 82 degrees so now temp gauge is reading even hotter when running solo. Radiator seemed to be in good nick. Any help or advise on the temp or petrol engine gratefully recieved as cant get hardly any info of ford or nissan.

 

[ronypony]

So things are fine as far as engine temp is concerned when not under load..temp rises when towing especially when uphill...engine is working harder..revs will fall as you slow going up incline and factory fitted viscous fan will not be providing as much cooling....my inclination would be to fit additional cooling in the form of an electric fan which will be controlled by rising temp of water as engine is put under load...a much more efficient way of cooling your engine than the factory fitted viscous fan. Many caravanners find they need additional cooling.
Its an additional expense but the risk of head gasket failure due to overheating will be removed.

 

[rusty1]

Thanks, I will price this unit up today. Any ideas on heaters as i think i forgot to mention they only work on 4. i'm no mechanick so i dont know if this will effect engine temp. many thanks

 

[gadgetsyd]

Hi Rusty1, I had a similar problem with my T2 in hot weather, I have now fitted an extra electric fan and it seems ok now. The kit came from kenlowe.com, they were very helpful, not cheap at £138 but better than a cooked engine. The 10inch high performance fan is thermostat controlled with manual overide, yours might need a different kit as that was the only room left on mine. Syd

 

[andrewk]

Are you *certain* that the engine temperature is actually too high? Dunno about the Terrano/Maverick but most cars are seriously over-cooled and this just shouldn't happen.

A car I once had developed similar symptoms, I changed the thermostat, I flushed out the radiator, I flushed the cooling system completely and changed the coolant. I worried about it for weeks. In the end, I had a dose of common sense. I removed the temperature sensor, stuck it in a pan of water on the cooker and with a multimeter measured the resistance of the sensor and with a thermometer dangling from a piece of string the temperature of the water as the temperature rose. I noted all the readings and drew a graph of resistance against temperature.

I then refitted the temperature sensor and ran the engine on tick over. Sure enough, the temperature gauge needle had swung well into the hot end after it had been ticking over for half an hour or so. I then measured the resistance of the sensor with the multimeter - and looked up the water temperature from the graph I'd created earlier. Guess what - perfectly normal!!!

Before spending good money on something you may not need, it might be worth investing in a new water temperature sensor. If you've attended to all the other likely candidates - such as hosing mud out of the radiator fins and changing the thermostat - and if the water doesn't actually boil and blow steam all over, I think I'd try that next. The gauge might just be telling fibs.

Cheers
Andrew

 

[ronypony]

Hi Rusty1

After replying to your initial post I decided to look into your overheating problem a little more by doing a search on this site for 'overheating'.
Some of the previous posts I read on the subject threw up some interesting possibilities for why your engine may be overheating under load but not under mormal driving conditions.

Before fitting electronic fans as I suggested it may be worthwhile exploring one or two other possibilities..e.g.

1. Check condition of radiator...even if radiator appears to the eye to be
in good condition it may not be...any corrosion, silting of radiator
could have very detrimental effects on cooling capacity.

2. Check water pump which are a known weakness (according to posts on
on this site). Apparently they can spring a small leak underneath the
pump which is difficult to detect.

3 The cooling fan is of the viscous type and the coupling is of course
part of the water pump..apparently the coupling can weaken over
time and become very inefficient. When engine is under load and
temp rises the coupling should ensure that the fan is doing its job
but this may not be the case. If you discovered the pump was
knackered an after market Quetin Hazel water pump costs in the
region of £65 compared to the £160 Nissan would take off you.

4. Do you lose any coolant after a tow ? If you do then you have a leak
somwhere. Check the thermostat housing..is it plastic or metal..I
have read that the plastic housing can become distorted with heat and
cause a leak.

5. Maybe a good flush out of the complete system would be a good idea
to ensure all water ways etc are running clear.

6. Additional cooling capacity through fitting electric fans is perhaps
desirable but may not be totally necessary. The vehicles were designed
with viscous fans and a huge towing capacity...you would think that
they would not need after market additions.

7. Is your Mav fitted with an intercooler ?

The problem with your heater only working on setting 4 'full blast' is an easy fix. Get your head in under the dash on the passenger side footwell.
Look up and you will see the heater motor (a large round thing). To the immediate right of the heater motor you should see an electrical connector/socket type of thing held in by two obvious self tapping small bolts/screws. Remove these two screws and withdraw the 'rheostat' card.
Seperate the card from the connector. Look carefully at both sides of the rheostat card (this controls the speed of the heater motor). You will more than likely see a 'burned out track' on one side of the card. Clean this up with a bit of fine sand or emery paper. Put a blob of solder across burned out track. Refit the rheostat and try your heater settings..the heater should now be working on all settings :smile:
BTW a new rheostst card costs about £35 off Nissan...much cheaper to invest in a soldering iron if dont already have one :lol:

 

[Rick1956]

Teranno's / Mavs are well up to towing without overheating in the hottest of conditions, if yours is, there must be a problem somewhere, touch wood it will be an easy fault to sort.After replacing everything possible when mine kept boiling it turned out to be a disintegrating rad core.
Be lucky :lol:

 

[Fishcom]

Hi;
Jusy had exactly the same problem with my TD: towing a stock trailer at 50mph made the needle tickle the red line, OK at anything up to 80mph without a trailer, but at 85, temp steadily rising, slow down, temp normal again etc. etc.,
Radiator looked OK until it was out, but fins absolutely knackered on close inspection.
Brand new rad £80.95, I'd be interested if anyone thinks this is cheap or dear: Let me know & I'll pass on the dealer's info (next day delivery £10)

 

[Rick1956]

£80 is a good price, the cheapest I could get at the time was around £100.

 

[jkata]

I have a lWB2.7 t2 and had a problem like this.

I took it to the garage and they checked everything. Radiator, fan etc.

They chased the fault back to the temp sender near the cooling manifold, it had a bad connection.

Changed that and I had no temp reading at all- turned out the new sender was knackered too.

Third time lucky, no problems now.

 

[andrewk]

They chased the fault back to the temp sender near the cooling manifold, it had a bad connection.

Changed that and I had no temp reading at all- turned out the new sender was knackered too.

I still think this is the favourite if there are no symptoms other than the gauge reading. As I said above, it happened to me too.

Oil pressure sensors are another that go relatively frequently. I had to replace two in the Trooper I used to have. There was nothing wrong with the engine, the gauge was just telling fibs.

Cheers
Andrew

 

[jkata]

Temp guage readings went really mad, would be cold one day then super hot the next- didnt seem to matter where I was driving apart from it came back to normal on idling.

I guess there was a poor/bust connection and at higher revs it was shaking it about a bit

 

[rusty1]

Thanks for all the help. Ithink i'm gonna start with the thermostat sender and work backwards. I'll do all the tests before I shell out hard cash. Again many thanks and I'll keep you all informed when i solve it. cheers Russ.

 

[Jocky]

I'm 99% certain thats its the viscous fan not kicking in. If it is working you can hear it start and it cools the rad quickly. If you never heard it start its not working. If you don't know what it sounds like its not working.

There are a few threads on the subject.

:smile:

 

[jkata]

Good option to see if the fan is kicking in- when it gets hot stop straight away and have a look under the bonnet.

 

[jkata]

Someone else may know better however I think in the workshop manual there is are the figures for either voltage or impedence for reading off the temp sender with a multi meter, this should give you an idea as to the state of the sender

 

[andrewk]

Some of you guys are confusing the hell out of me.

My understanding of viscous fans is that they behave exactly like fixed pulley driven fans, except that they are supposed to slip at high engine revs due to the viscous coupling and hence reduce the overcooling that would occur with a fixed fan and also, to some extent, reduce the amount of engine power consumed by the fan. I've no idea what you mean by the fan "kicking in" - they run all of the time that the engine is running. The amount of power consumed by a fan increases as the cube of fan speed. As the engine speed increases, there comes a point when the fluid coupling will not transmit enough power to further increase the fan speed - whereas, a fixed fan would just be driven faster, consume more power and overcool the radiator/engine.

If/when viscous fans fail, I think the car will overheat when stationary or at low speeds. As a rule, engines do not need fans at all for 95% of the time and definitely not when running at speed - so the behaviour of the fan is irrelevant in this case. If you stop the engine, you'll be able to rotate the fan by hand whatever the engine temperature. This is just normal behaviour.


Cheers
Andrew

 

[andrewk]

Someone else may know better however I think in the workshop manual there is are the figures for either voltage or impedence for reading off the temp sender with a multi meter, this should give you an idea as to the state of the sender

The most certain way is to do what I suggested earlier, calibrate it yourself with a thermometer, multimeter and a pan of hot water.

Cheers
Andrew

 

[andrewk]

I thought fan must be working as when i pulled over temp would drop with engine running.

Correct.

Cheers
Andrew

 

[jkata]

Personally I'd disagree with that being the right way.

Much better to test the sender in situ under conditions most similar to its normal environment.

Just my opinion