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Discussion Starter #1 (Edited)
Hi,

a few weeks back, my Civic 1.5 started overheating out of the
blue. As many before me, I suspected the thermostat first, but it
wasn't it. I checked the coolant level, was ok. Bled the system,
checked the fan...even changed the water pump. Still overheating.
I began loosing my mind as it allready cost me a lot of time and
nerves. I came to a point where I dont see what to do anymore...

Here's how it went (a bit long, but please bear with me)...

The car I bought in February, is a Civic 1998 Aerodeck with the
E-Vtec, 1,5 LS i 16V engine. It was in good general condition and
with a fairly good service history (not official unfortunately).
It was running like a dream until...

Pinking / rattling sound under slight load

..it started sounding like something was loose when it was warmed
up and under moderate load. The sound disapeared with throttle
pressed or decreased a bit. I did next things:

- oil + filter
- fuel filter
- spark plugs
- spark plug wires
- distributor cap
- distributor rotor
- air filter
- timing adjustment

The problem was still there. As Im a person that has to fix
things, I decided to check the:


- valve clearances

Nothing changed. I tried different fuel - no evident difference.
Failing to find out what the problem was, I decided to just keep
driving. It progressivly got worse (more enhanced, louder) but
everything else was ok so it didnt bother me. After one seriously
quick 1 hr drive on the highway, the car started...

Overheating

As soon as I stopped at the traffic lights, gauge started
climbing dangereously close to the red zone. When I drove back
home I had no issues. A few days later it started again. This
time I decided to check whats going on:

- I replaced thermostat 2 times
- topped out coolant

It was still overheating

I decided to give a go with yet another thermostat (ended up with
three fully working ones - gave them a test). Time for..

Big service - water pump

- replaced all the belts
- replaced the tensioners
- replaced the water pump (btw, all the stuff I took off was in
mint working condition)
- took off the radiator, cleaned it, pressure tested it
- checked the pipes where I could for leaking
- adjusted valve clearances and timing again
- replaced all the coolant and bled the system

I was almost sure this would be it - but no. It still overheats.

I did manage (had looots of time) to find out next:

- when starting from cold and running the engine with car parked,
all works ok. Fan kicks in, temp. gauge never climbs over 1st
third of the scale even with my girlfriend in the cabin, pushing
the throttle down for 30 minutes (around 3K rspm).
- when I drive off and the gauge starts climbing up, I park the
car, engine running, fan not working.
- most of the times, increasing the rpm while driving will cause
temp. to drop, but not allways
- sometimes temperature jumps up or drops down (again, while
driving) from no apparent reason > driving constantly the same
- if I jump-wire the thermo switch located on the thermostat

housing, fan works ok, so relays and fuses shouldnt be an issue
- the plastic reservoir is all wet around the top eventhough I
made sure its tightened correctly. Also, the coolant level in the
reservoir gets way too high after a while...
- thermostat works ok as the lower pipe gets hot in time
- temperature gauge (sensor and sending unit) work - when the
gauge shows its hot, it is hot indeed
- there are some air bubble in the system when running idle, but not a single one when I increase the revs and hold them there...

Now, Im a DIY guy, but still have some questions regarding all I
wrote up:


- could it be that thermo-switch isnt functioning ok and it
sometimes works, but fails too when it really gets hot?
- could it be the reason is failed ECT sensor located under the
distributor housing?
- does the ECT sensor send data to ECU and then ECU adjust the
fueling mixture, meaning a failed one might cause ECU to "create"
a mixture too lean and thus engine would get too hot? This would
also make sense in corelation with my "pinking" (= preignition?)
problems...
- could the reason for both problems be a carbon build up inside
the engine, causing it to run too hot even for a flawless cooling
system to cool down?
- could the cap of the radiator be faulty and "let" the coolant
run into the plastic container before it hits 1.1 bar > the
pressure in the reservoir of course would be too high and it
would leak through the cap?
- could the reason for all that be a radiator not in top condition? Its not leaking but some of the cells have been smashed in the bottom...
- I bled the system twice, but could a bigger air pocket trapped in the system be causing this?
- is the cooling fan on the Civic a two or a single stage one?

I know, many questions but I really dont know what to do anymore. I bought this car to be a low budget transportation device so an idea of visiting a Honda garage scares the **** out of me...Any ideas what else might be causing it?

If everything fails, Im gonna go to a mechanic and test the compression and A:F ratios and see from there on...

Many, many, many many ***** for help guys!


Best,

F
 

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Change the coolant sensor.. The have a habbit of giving false readings.. And would cause rich fuel air ratio. Give it a go as this resolved my problem before. :)
 

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Cockup Specialist
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12,885 Posts
The coolant is a presssurised system.
It needs to be under pressure to raise the boiling point.

1. Get a new sprung cap with pressure release and make sure it seating properly.
2. Drain and backflush the whole system to get rid of any gunge and sludge from the heater system....make sure its on max heat.
Make sure the vent bypass isnt blocked if you have one.

Coked engines cause pinking as the compression increaeses....bg44 will fix this.

But yes the 1st things I would have changed would have been ECT sensors, cap and thermostat.
 

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Discussion Starter #6
Many ***** guys,

I will go to a mechanic and first make sure compression and AFR are ok...will see how to move on then!

BEst,
 

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Many ***** guys,

I will go to a mechanic and first make sure compression and AFR are ok...will see how to move on then!

BEst,
A friend told me that he had a simmilar prob and noticed the water pipes were fitted the wrong way round. Do you have a sludge in with your oil also does your sparkplugs have oil on any of them ?
 

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Discussion Starter #8
No problems with that. Spark plugs ok, no oil in water no water in oil, nothing sludgy...
 

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Discussion Starter #9
Well, the mechanic didnt actually measure it (didnt have the equipment gah), but said its definately the headgasket. I will order the compression tester myself and measure it to be 100% sure and see how to proceed...
 

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Clutch pedal guru
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Headgasket job shouldn't be dear on a 1.5 Honda engine. They're pretty simple really
 

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Discussion Starter #11
I do believe it shouldn't, but as this car was intended to be an extremly low cost one I think Im going to skip it. Besides, car needs more than just that: new brakes, suspension bushes, tires, shock absorbers, AC compressor just died, not to mention it was crashed two times (not my fault! :))...

Best,

F
 
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