[solved] Help! B16A2 heating up on VTEC After thermostat changed

[EG52NV]

Hey guys, I just changed my thermostat today because car wouldn't warm up. To my surprise when I took apart thermostat housing the car wasn't even running a thermostat. :(

So I replaced it with a CPC thermostat and changed the coolant. Now car warms up fine and needle sits at halfway point. Have checked and thermal fan is working also check that the thermostat is opening because bottom hose warms up.

Now here's my problem. I can drive around, idle the car and temp needle does not move from the middle position but as soon as I hit VTEC (bang out 2nd 3rd and 4th gears the temp needle starts rising and it even reached like a few lines off the HOT bar!! After this if I stay off VTEC and just drive around normally, temp needle eventually drops back down to 50% mark (I think it goes down due to thermostat opening.)

Engine apparently has CTR cam shafts and Skunk2 cams.

Question is will getting a lower temp thermostat help? (I googled and a lot of ppl don't recommended this on daily car) Or is my problem elsewhere?

Car never heated up prior to changing from "non-existing" thermostat to a stock thermostat.

[EG52NV]

Ok just read about the air bleed nipple, I may not have bleed the cooling system properly... Because thermostat takes forever to open up like gotta idle drive car for 10mins before bottom hose gets warm.

Other google searches say to bore out the air rattle thing in thermostat so that a lil bit of coolant is constantly flowing through thermostat to evenly warm up thermostat.

Upon visual inspection car is not leaking coolant

Fan will automatically switch on even when temp needle is at 50% mark so I know fan switch is working and kicking in at normal opp temps

Notes: Car never overheated once when it was not running a thermostat hence I think waterpump is fine, this is even if I I had booted it on VTEC a few times temp needle would only go down below 50% "not up" so no overheating issues there.

[beeza]

U could try a low temp radiator fan switch and keep the thermostat..Don't know if it will work but it does keep things a lot cooler.

[TODA AU]

The thermostat was likley removed in the past by the previous owner as a bandaid rather than fix the issue.
You may still have coooling system issues, maybe blocked radiator etc...
Did the engine have coolant in it? or just water?
But before you do anything, try replacing the single wire temp sensor for the dash (side of head under dizzy)
& also check your engine earths. (0.5 ohms or less)
It may just be something silly with a quick fix.

[EG52NV]

The thermostat was likley removed in the past by the previous owner as a bandaid rather than fix the issue.
You may still have coooling system issues, maybe blocked radiator etc...
Did the engine have coolant in it? or just water?
But before you do anything, try replacing the single wire temp sensor for the dash (side of head under dizzy)
& also check your engine earths. (0.5 ohms or less)
It may just be something silly with a quick fix.

Engine had coolant in it before i changed the thermostat.

This morning I tried bleeding all the air out of the system, started car, radiator cap off, heater on, idled the car for at least 20 mins! car warmed up to the 50% mark but thermostat never opened (bottom hose remained cold) and radiator fan never came one. so I closed the radiator cap and took the car for a short drive about 5 mins (no hitting VTEC), and then I pulled over, temp still normal at 50% mark I then felt the bottom hose and it was now warm therefore thermostat must have opened when the car being driven. Also since I marked one of the fins on the thermo-fan with a marker I know the fan also turned on during the drive as the fins changed positions. (I've also actually seen the fan in motion so it definitely works)

further test included taking the car for a longer drive about 15 mins (did not take revs past 5500rpm) and everything was perfectly fine temps were 50% no overheating what so ever, then at the end of the drive I banged out about 2 gear worth of VTEC and surely temp gauge starts rising.

Therefore I've put it down to car will heat up dramatically when in VTEC. and it seems the thermostat is taking forever to open up which is why I think with the current mods CTR cam shafts and Skunk 2 cams (according to previous owner and VTEC does come in HARD!) I may need a lower temp thermostat.

[EG52NV]

will also take your advice and look into changing the single wire temp sensor for the dash (found where it is when I was looking for the non existent air bleed valve this morning)

[EG52NV]

FFFFFFFFFFUUUUUUUUU after market CPC thermostat! POS was actually faulty!

So it ended up costing me $100 for Good Peformance to check over the car, did a cooling system pressure check for head gasket leaks and when that passed with flying colours next thing they did was change the thermostat over to a genuine Honda one and it fixed the over heating problem!

FML! I should send CPC the bill as well as get a refund for the faulty thermostat!

[Bludger]

what was faulty?

It opened and closed right?

I've never had a problem with their product.

[EG52NV]

what was faulty?

It opened and closed right?

I've never had a problem with their product.

Thermostat was doa. Even when I put it in boiling water it would hardly open

[EG52NV]

also, had slight leak in HG which caused car to heat up on hard runs, all fixed with a new HG

[mocchi]

good to hear resolution. yeah byuddy!