Hi all. Im' a big blogger but new to the forum. Looking for someone to help. Just picked up a civic to boost and mess with as a second car and working out the bugs... currently overheating.

Vehicle::
1998 Honda Civic LX
1.6L naturally aspirated (for now )

Problem::
Overheating

Remedies to date:
(1) new fan switch (was bad)... still overheated but much better
(2) new stock temp thermostat... still overheated (no change)
(3) new 79degC temp thermostat... can overheat when I beat on it (much better operating temps all around)
(4) new OEM radiator... same condition but I feel better about it for some reason
(5) new head gasket and waterpump cause I'm pissed off and getting serious... (did valve adjustment, mounts, all belts and other un-necessary stuff for the heck of it while i'm in there)

So what gives guys? Does this year make/model car just overheat when you beat on it?

When I beat on it, it quickly hits >105degC and the coolant starts to boil over into the bottle. I already checked for coolant leaks and she's solid. Considering new coolant lines and all aluminum radiator but starting to think I'm missing something. Pissed off now and ready to throw a new motor in it... want it purring cause I'm boosting it this summer. And if I boost it and this car is know to have a poor cooling system... should I add a larger/secondary radiator and secondary in-line water pump?

Thanks for reading.... and please chime in!


def of "beat on it": any extended periods (>1.0 minute) of WOT throttle in high gear (5th) low RPM (say 2000rpm ~100% duty) climbing steep grades (~10%).

 

could be possible that you block is no longer flat and is warped. possible new block? Just ah thought. It happened to me in my 2003 civic

you had your head resurfaced corect? also you bolt new bolts I hope?

 

You should not be climbing mountains in 5th at 2000 rpm. There's practically no hp there, the engine likes to spin. Get used to dropping a gear, your engine will be much happier and last longer pulling hills at 3000-3500. The Civic engine is not a V8 that can lug along, it's best to never operate it below 2000 when giving any gas at all.

Is the system completely full and staying that way? Before each trip with the engine cold open the radiator and check it should be full to the top. If coolant keeps inexplicably going away, this is likely a small leak in the head gasket.

Do not use thermostats lower than stock temperature, if the engine does not warm up to design temperature the ECU will stay in "open loop" warm up mode which means low mileage and increased emissions.

Are you sure the fan works? Jump the fan switch-- fan should now start immediately when you turn the key on-- and test drive with the fan running all the time.

Also check your spark timing with a light, late timing will cause low performance and fuel economy and also generate excessive heat.

 

@rippee42

I was thinking head gasket too. I re-torqued the head bolts properly but I never checked if there was coolant in the thread hole! I've heard this gives improper torque readings if that is the case... could lead to a leak. However, I am not loosing coolant... perhaps just exhaust gases are squeezing into the coolant reservoir high chamber pressures. .... I think I will pull off the Valve cover and remove each head bolt one-by-one.. clean them... vacuum out any debree in thread holes... and reinstall new clean lubricated head bolts. I will re-torque them in the appropriate pattern.
(don't think pulling the new gasket is justified since I only have like 500kms on it so far and no leaks under cylinder pressure test ~200psi.... also... I did not detect ANY warpage or irregularities of the mating surfaces when installing). Still a bit stumped.... but heck... I might as well do a valve adjustment while i'm in there

@mk378

Thanks for the comments. Some good ideas.

In general.. I've just been driving in high gear/low rpm to test the cooling system (not my typical driving habits). Also, I checked the fan by jumping it already (just as you suggested). And I did measure that the fan now comes on at design temp (i used my obdII to check coolant temp when newly installed fan switch was in while idling and it performed well).

Also... timing is dead on. It was actually advanced a tiny bit from an overtightened timing belt. But I set it up properly when I swapped out the water pump and installed the new t-belt).

Finally... low temp switch. I know the mileage won't be as nice... but I'm used to driving <15mpg automobiles (I know... sick right). I know it's not ideal... but I intended to run it a bit cold cause the future turbo is gonna make some serious heat!




Thanks guys for your tips/ideas.

Hopefully this head bolt business will have a positive outcome (highly doubt it).

 

Don't mess with the head bolts unless you confirm leaking. Then you would of course need to take the head off and replace gasket. You can go back and tighten again to recheck the torque, but if you ever loosen a bolt you have to take the whole head off and replace gasket.

One way to check for small leaks is to start the engine cold with the radiator cap off and look for any bubbling in the radiator when you rev it. There should be no action in the radiator at all until the engine has warmed up some.

 

do you think backing off the head bolts will force me to re-do the head gasket? I'm pretty sure at this point it IS the head gasket... I must have done something wrong or somehow did not detect imperfections/warpage in the head.

I planned to first try to remove and re-install the head bolts. Since I did a thorough inspection of the head... and took my time to install correctly... I feel like it's a torquing issue. If any coolant was in the thread holes (forgot to check ), this may have contributed to improper torquing. I hoped I could back off about 50% of the torque on the bolts (in the reverse torquing sequence as installation) then remove and replace (back to 50% torque) one bolt at a time. This way I can clean the threads and remove any coolant in the thread bolts as required. I hoped this would keep the gasket in place and final re-torquing to specs could be done in the same sequence. Should I try this? Or just re-do the whole job and purchase a new head gasket and machine the head? (really don't want to do that)

ps. I took it for a rip today and when I got back quickly inspected the fluid under the radiator cap to look for tiny tiny bubbles in the fluid. Sure enough... there was. Almost positive now that I have a tiny leak from cylinder to coolant that only leaks exhaust gases (only at high cylinder pressures) to the coolant chambers. Dang.

Waiting for you guys to chime in. PS. If you think I should do the gasket... looking for suggestions on what type of gasket to use if I plan to turbo. Thanks!!

 

...well. As a mech engineer with many years of automotive design experience (and a lazy one with a huge "to do" list)... I figured it would be worth a try. It worked perfectly. 30 min repair.



Basically... this is what I did
(1) valve cover off
(2) backed off all head bolts ~ 30 degrees CCW (assumed to release ~25lbft torque)
(3) removed head bolt #1 (centre) and vacuumed out thread hole. Oiled head bolt and re-installed to 22lbft torque.
(4) removed #2 head bolt and repeated process. Did the rest of the bolts in the recommended torque order.
(4) I discovered that 2 head bolts had oil inside the thread holes when I originally installed the gasket and must have given me improper torque readings on original installation!!
(5) once all bolts in... torqued to spec 49lbft in suggested order.
(6) went to 59lbft in suggested order just because. My instinct told me to do it (probably cause I'm lazy and REALLY REALLY don't want to do the whole head gasket job)... but my eng backround told me not to.... but I did it anyways
(7) compression tested all cylinders to 175 psi... passed with flying colours (yes I spell like a canuck)
(8) drove it hard and temps never went over 92deg C (as per obdII reader) !!
(9) checked coolant overflow and no small bubbles

SOLVED!


thanks all for chiming in !!