geekdude

Hi everyone. I have a 93 civic with JDM d15b vtec and it has been overheating lately. Its had a slow oil and antifreeze leak for some time. but it started blowing smoke out the exaust on high revs and overheating. I took it to a shop and had the headgasket and watterpump changed, as well as the spark plugs and wires, they also changed a bunch of seals. This didnt seem to change much. i took it back and they "rewired the temperature sensor". from what I can see it looks like they rewired the ECT sensor. later on I found out that I was running on winter oil. (5w30) and its been realy hot lately so changed to 10w40 this actualy helped a lot with the burning oil. It hardly does that anymore. I noticed it did not turn on the fan even when the temp is into the red. we tested the old fan switch and it looked to be a bit out of spec according to the manual. but i replaced the temp switch and the fan still does not turn on (unless jumpered). I bought a infrared thermomitor and found out that even when overheating, externaly anyways the switch does not reach the temperature where it would switch the fan on. we opened up the radiator and ran the car for awhile. we could tell when the thermostat switched on and when under moderate load i noticed large bubbles about a half an inch in diamater come up ocasionaly but it did not change with the amount of revs. also there is a light grey film on the inside of the coolant system and there is dark stuff that floats to the top of the antifreze. some people on the internet say this could be because the hoses are ageing and falling apart on the inside. also we checked the compression on all the cylinders and they checked out. The garage we took it to said they thought it was the piston rings, but i'm not sure if I trust them. oh and also I changed out the radiator a few months ago. its a racing radiatior. I used a oil cooler from orileys for the transmission cooler because the radiatior didnt have one.

firehawk618

If your fan isn't turning on by itself you need to figure that out first.

It could be the fact that coolant isn't circulating in your engine for some reason.

Maybe the new water pump impeller has come apart from the shaft and isn't spinning.

Maybe the thermostat is stuck closed.

It's easy enough to test the radiator fan circuit.

Put an appropriate resistor in place of the ECT sensor and it should trigger your fans.

I do not have the ECT specs on hand, maybe someone else will chime in with the right resistor to trick the circuit.

geekdude

sorry ive been busy lately. from the schematic i read, that i found in the honda manual, i assumed that the fan was just tripped by the thermal switch which i replaced. jumpering this switch turns on the fan. but this is not susposed to trip until it hits 207. I havent seen the switch get that hot. even when the temperature is all the way to the top of the gauge on the dashboard i have not seen the thermal switch get above 199. I would think the fan would engage sooner than that. there was a wire going to the ecu on the schematic. i suppose the ecu could ground this wire and trip the fans that way as well. we took the cap off of the radiator and observed it while the car heated up. there was definately a point where it seemed like the thermostat opened up and it seemed like at that point the watter pump was working. it caused more splashing in the coolant and it started to get warmer. also the level of coolant rose with rpms. I dont know if its susposed to do that i havent looked at the level of coolant in a radiator with the car on before. there does seem to be a dark grey substance that floats to the top of the coolant as well as a light grey substance deposited everywhere there is antifreeze, but i have heard that may be due to the rubber hoses ageing. but yeah I guess the ect sensor is the best place to look for now. Thats what the garage I took it to was messing with

geekdude

ok so I tested the coolant temperature sensor. started the car and let it warm up for a bit. The sensor was about 120 degrees and it read about 312 ohms which is in the 200-400 ohm zone where it was susposed to be according to the honda manual. I also noted 5 volts to the red/white wire and ground on the other wire. I am now looking in the chilton for schematics. i suspect somewhere in swapping out the engine some time ago perhaps a wire got crossed somewhere

tony_2018

honda helms manual has schematics.....

geekdude

I have a helms manual, a chilton, and a pdf of the official honda service manual. I found the info ineeded to test the wiring
I seem to have some resistance somewhere in between the ground wire of the ect sensor and where it plugs into the ecu. im looking into that. but thanks for the tip on the ect. i didnt think that had anything to do with it.