JasonHZS

Hi folks, I've been lurking the forums for a while now and I've decided to share my problem since I haven't been able to find an answer.

I had a P0128 code that would come back despite replacing the thermostat twice, and I discovered a crack in the engine block. So as per TSB 10-048, I managed to get my engine block replaced for free.

Unfortunately, the P0128 still persists, and since the engine block replacement, I've had a power steering fluid leak (replaced two rubber seals), one coolant hose which sprung a leak (replaced it just left and under the air cleaner) , and another coolant leak due to a factory coolant hose clamp that got loose (replaced that too). And just for good measure, I had the thermostat replaced yet again since the previous replacements were done by the last owner.

During my last visit, the mechanic told me that based on the upper radiator coolant hose, the pressure is too high (its really hard to squeeze, but it isn't ballooning) and yes the car was warm, two notches under the middle mark of the coolant temp meter.

Due to the history of engine overheating once, since Honda didn't replace the head cylinder itself, I feared that there was some sort of leak in the head cylinder causing over pressure in the coolant system. So I took my car back to Honda today, only to be told after supposed pressure testing that the engine is fine, but they found three coolant hoses with tiny pin sized holes in them. Their only recommendation is to replace all the coolant hoses, the thermostat, and the fan switch.

Just wanted to ask around and see if that makes any sense to anyone else, because I'm worried that these holes in the coolant hoses are just a result of high pressure in the coolant system.

Help!

Here's a list of stuff that's been done, checked or replaced
- Head cylinder was untouched as far as i know, the old oil stains are still on it from the one time it overheated
- Head gasket was replaced, brand new.
- Engine block was replaced, brand new.
- Thermostat was replaced, genuine Honda
- Coolant shows no oil residue in it, seems clear
- Oil dipstick is fine, doesn't have the frothy or milky look that indicates coolant leaking internally
- Upper coolant hose is easy to squeeze when cold, gets really hard when coolant heats up, not sure whether the pressure really is abnormal.

ezone

Check the temp sensor in the bottom of the radiator.
Could be just a bad sensor, but also check to see if it has leaked liquid through into the wiring connector and started corrosion.
If one has a really good scanner you might be able to witness the actual temperature value be inaccurate at times.


There is also a software update that addressed false P0128 code, a dealer would have to connect their scanner equipment to the car to see if it has been updated or not.




Pressure buildup as the temperature increases is normal, the cap will limit max system pressure to about 15 PSI.

Holes in the hoses are likely the result of someone careless replacing the engine block IMO or some other physical issue. Otherwise, the hoses are quite robust in terms of lifespan.

Allowing it to overheat can cause damage, blow the head gasket and warp the cylinder head.. Hopefully whomever replaced the block also measured the head before reusing it.

HTH

JasonHZS

Hi ezone! Thanks for the thorough reply.

Yeah I was just reading up about a possible stored code issue, as well as a possibly bad sensor. I'll explore these two options, and update the results here.

Thanks again!

TonyCivic

Hi JasonHZC,

Can you provide more details on the stored code issue? My dealer told me that my newly replaced , non-OEM, thermostat was "binding." I did not quite buy into this theory since they later said that the never checked to see if it was binding. Their decision was based on experience. Also, I put the thermostat in boiling water and it operated just fine.

JasonHZS

Hi Tony,

What he probably means by binding is that the thermostat is 'stuck' in either the open or closed position. If it's stuck open, your engine should have trouble warming up the coolant to the midway point on your dashboard. If not, your coolant will be running hotter than usual.

I caved and brought my car in to a Honda dealership to get it fixed once and for all. Turns out that some mechanic replaced my fan switch with the wrong type, which was causing my cooling system to overcool my coolant.

Ever since I got that fan switch replaced, my car has been working fine. It wasn't the thermostat after all, but I got that replaced with a Honda OEM one anyway.

Hope this answers your question!