pro306

I'm a very experienced mechanic of over 20 years and this little car is kicking my @$$&%#!!! a friend of mine has a 96 dx civic that started trying to run hot. temp hand goes about 3/4 way. i replaced t-stat went ahead and did watr pump timing belt fan switch temp sending unit still same problem. so i replaced the head gasket. i still have the same symptoms. the radiator was replaced sometime in the recent past. the fan comes on but not always at the same temp. i check the temp with a ir gun at the t-stat housing. initially it comes on around 197 then after cycling a few times it slowly creeps up to 210. the gauge in the car steadily rises. i notice that if i run the heater fan it runs cooler (witch it should) but that doesnt always remedy the problem. also if i move the temp from hot to cold the temp rises really fast. any way I NEED HELP!!! SOS!!!

95Sedan

my honda heats up really fast, as in driving 2 minutes it's at running temp already, 210 doesnt seem like overheating though?
you said you replaced the sending unit. Where's the gauge at when it's "over heating"
also have you burped the system. sounds like you have alot of air in it.

pro306

The gauge will eventually go all the way up to just below the white line at the top before the red mark before i kill it. i used one of the funnels you attach to the radiator ran it cycled several times let cool with funnel on then cycled again. heat blows real hot. the 210 is with the ir gun at the t-stat housing.

grumblemarc

iTrader: (4)

Bleed air from system? Check for head warpage?

pro306

yes machine shop checked head and did valve job

grumblemarc

iTrader: (4)

What else have you checked? Rad cap? Sensors? Bottom hose staying cold? Never said about the sir in system.

pro306

what sensors are you suggesting (honestly hoping i missed something). i replaced the fan switch and temp sending unit. and using the funnel on the radiator and front end elevated plus the heat blows HOT. i would think all air is out of the system.but it does act like there's still air in there somewhere. at least thats what my first guess would have been. ive done 3 warm up cool down cycles. with the funnel on the radiator. if there is air in there still who knows. but can say ive never had this much of a hard time bleading a system if there is air in it still.

S2BumpsticksGSR

There's a little nipple on top hose cylinder head side to bleed air out w/front of car elevated. Was the deck of the block checked for warpage when the head was off? The cylinder bores have a tendency to "sink" into the block on high mileage Hondas. Edit- hmm didn't know the d's don't have bleeders. I thought my crx did, but it was different gen and so long ago I forgot.

pro306

For some reason this engine doesn't have the bleed nipple/valve. It's a non vtech engine. You got me on the cylinder part. I've never heard of cylinders "sinking" in the block. Guess you learn something new every day. I can say the cylinders and deck visually looked really good.but I did not ckeck with my straight edge. Are these heads bad about cracking. I just got off he phone with the machine shop. The didn't pressure check the head. Not sure why but I hope that's not the problem.

grumblemarc

iTrader: (4)

No bleeder on the D-series.
Hope the head isn't cracked.
Time to run some leakdown tests.

JJT211

There isnt a bleed valve on 96-00 non-vtec's.

My fan normally doesnt kick on til 210 either, cooling fan switch is good. Its the thermostat that opens at 180ish.

Have you verified the actual temperature of the coolant with your IR during the overheating period? Verify your temp indicating system is accurate. Could be wiring causing the engine to appear to be overheating when it actually isnt.

I believe there are 2 sensors (one for ecu and another for the actual gauge) and then theres the cooling fan switch.

JJT211

Use a scan tool connected to ECU to verify your cooling temp sensor and and wiring readings against IR.

Use IR to verify your temp gauge and temp sending unit.

Basically just verify the engine is actually overheating as opposed to what the gauge says. If all 3 agree (ecu, temp gauge, IR) then you can eliminate indication at least.

The coolant temp sensor (ecu system) is on the thermostat housing. Fan switch is on left side of block undernethe distributor. I cant recall where the temo sending unit is though.

pro306

That's prety much what I was doing. I may be wrong but Ida swore the fan switch was on the tstat housing and the ect was on the head under the dist. The sending unit is under there to. If I'm wrong then maybe that's the problem. But kinda funny the fan switch and ect having the same plug??

Championship

Does the car idle fine? Does it putter from time to time?

If everything else fails, it's time for a swap, the pistons could be warped, head cracked, crack on the cylinder wall...list can go on and on..

pro306

it actually runs smooth. and has good power.

JJT211

The reason I know is because I made the same mistake too...

Thought I was changing the ECT sensor when I actually changed the the Fan Switch....when I bought the part I thought the Auto parts dude was saying it wrong...lol

j__rolla

Have you found the issue? I have the same exact problem on my 97' D16Y8, I mean exactly. Did compression, leak down, block test all negative. Really curious to see what you found.

JJT211

Damn you see....I did it again! You're right...fan switch is on T-Housing....Thats what i keep getting confused!

pro306

ok finally got it fixed. actually Sunday but its been a crazy week. as a last ditch effort I figured it would be easier to pull the radiator and back flow it instead of taking the head back off and to the machine shop again. there was so much crap in the radiator it was ridiculous. best I can tell someone put block seal in it. I put a new radiator in and no more problems. the gauge stays just bellow half way fans cycle consistently at a lower temp all is well.
thanks for the helpful suggestions and insight.