Spey

1996 2.2L VTec Automatic

Current Condition:
Idling in neutral, not hot enough to open thermostat.
Idling in gear; gradually builds temp., upper radiator hose gets hot and can feel lower hose get hot when thermostat opens (a bit before mid-point on interior temp. gauge). Upper radiator hose noticeably hotter (too hot to keep hand on), lower radiator hose can keep hand on. Both fans kick on just before mid-point on interior temp gauge, but fans will shut-down sometimes before they are able to control temp-build. Heater (interior) works fine (indicating there is some amount of flow).
Typically overheating when stopped in traffic (or at long stoplight).
Turing on A/C both fans will start (intermittently can control heat build).
Both with and w/o A/C on, fans will stop after a minute or two (fan re-start intermittently, independent of temp).
One fan starts after engine shut-down, when engine is hot.

Trouble Shooting / Testing / Results:
No coolant leaks (drips, etc.) at water-pump weep-holes, etc.
No milky residue (rad-cap, dip stick, oil filler cap).
New radiator cap.
Engine compression test good.
Leak-down % test good (tested at 90psi air pressure into cylinders at TDC).
Pressure tested cooling system to 15psi no leakage.
Fresh Coolant S.G. tested 265-F (full flush inc. engine, radiator, heater core).
Cooling system purged of air at air-bleed on thermo-housing.
Thermostat passed boil-water test fully open by 198-F (replaced with new OEM 172-F thermo).
Fan sensor (thermo-housing) passed boil-water test, continuity at 199-F (replaced w/tested new sensor).
New Radiator (previous hairline crack drivers-side of filler-neck), New radiator cap.
Jumper wire fan always runs fan.
Fan relay tested working in the power-window plug (same relay part #).

Appears problem may be that there's not enough flow circulation from the water-pump to push hot coolant back through lower radiator hose, past fan sensor and through thermostat (I am assuming hot coolant exits the upper front of the motor into the upper radiator hose and then is pushed back through the lower hose past the fan sensor then through the thermostat).

Any other troubleshooting …?
Is there a way to test the water-pump performance without removal for physical inspection?

--------------------------------------
*Update/Additions (since original post):
2012-7-1 Combustion Gas Test (pass - results referenced in post below).
2012-7-1 Water-Pump Test (Questions - results referenced in posts below - video added of 1st & 2nd pump test).
2012-7-2 New Lower Radiator Hose (was un-needed based on visual interior inspection - notes in post below).
2012-7-4 New Water Pump (impeller vanes were corroded badly and partially missing) Flow improved greatly - notes in post below.

tim73

Almost sounds like an air pocket. I say that because the fan is coming on after the engine shuts off. Anyway, you said OEM 172 thermostat, do you mean a honda thermostat? Just making sure, as I have had several non-honda tstats give me problems.

Spey

tim73,
Thanks for the reply.

Yes, OEM 172-F thermo (Original Equipment Manufacture - Honda - 172⁰ Opening / 196⁰ Fully Open Thermostat) vs. OEM 180⁰ and/or after-market thermostat. I took one look at the after-market thermo's and just put them back into their box. Appreciate your comment related to previous issues you've had with non-OEM-thermo's.

Yes, I agree seems like symptoms of air in the system. I’ve air bled the thermo-bleed multiple times (with heater on both with thermo open and closed with clear hose attched). Last time working on cooling system, rigged up 2-liter plastic bottle to the filler neck on the radiator and ran through a few heat cycles while also opening the thermo-bleeder with clear hose attached in further attempts to eliminate/reduce possibility of air in the system. This seemed to make an improvement, but still having intermittent hot-run issues. Will use the plastic bottle system again and see if can make additional improvements in overall condition (fully ridding air from system).

OR
Possibly …, the pump not being capable of circulating enough coolant to effectively cool the system …

*?* PUMP TEST *?*
*?* Still interested in any way of “testing” performance of water-pump in this vehicle *?*
Only way I can figure to effectively do this is to disconnect one of the coolant lines and extend it to maybe a foot above the engine with a dump into a catch container that has a return line attached (reasoning - that if the water-pump can pump to a pressure equal to 12” higher than the system that this might be valid indication that the pump has enough pressure for the system (but I have no idea how much pressure beyond heat expansion pressure the system should be capable of producing). I'd really lie to be able to eliminate the water pump via some type of performance test.

** Combustion Gas Test **
While the engine passed both compression and leak-down tests; in the back of my mind is still a consideration of an intermittent "combustion gas leak" to the cooing system that could be intermittent super-heating of the coolant. I may need to order up some of that sniffer-fluid (changes color in presence of CO2 from combustion gases) and sample the air inside the 2-liter bottle while the engine is running as a way of further ruling out intermittent combustion gas leak.

Appreciate any comments or thoughts on further resolution ...

tim73

Sounds like youve got a good handle on it. I would suspect the same things, could be a small head gasket leak, or pump not working like it should(Which i would lean towards) when was the last time water pump/timing belt was done?

Spey

tim73, yes head-gasket leak has been on my mind, but trying not to let that consideration cloud my interpretation of tests that I can run. Ultimately, I realize that there may be a small head-gasket leak (that was the cause other issues), but I need to first determine performance of the water-pump. If I remember correctly the water-pump has less than 40k miles (but this does not mean it's "good").

In my mind, really need to make determination on water-pump performance.


Video Link to Water-Pump Test:
http://www.youtube.com/watch?v=oP0I1JQUNc0&feature=plcp

Question: Does it appear that the water-pump is pumping effectively at this elevation?

7/1/2012 Testing
Results – “Combustion Gas Test”
Using “OEM Brand Block Test Fluid” appears to pass test without significant color change of blue fluid (except when accidental contamination of Test Fluid with small amount of in-taken coolant - whoops, but glad that I noticed and retested a couple times). The last and final test, I waited until after a full heat cycle of the cooling system then sucked up the gas (air, CO@, etc.) from bottom of my return funnel (see video example of return system I rigged up to understand), presuming that CO2 is heavier than air and would therefore displace any air in return funnel and CO@ if present would be at bottom of chamber.

“Flow Test” (video link above) began with luke-warm cooling system, heater-core control open.
Return Line approx. 13” elevation of upper radiator hose w/extension above radiator.
Upper radiator intake plugged.
NOTE: No coolant was being pumped out upper radiator hose until a few minutes into test. I had primed the hose up to approx. 2” from the top (so maybe 10”+ above engine outlet). I had assumed that as soon as the mechanical pump started (upon engine startup), that some coolant would be pushed out. Possibly because thermo-closed pump just spins but cannot overcome the fact that thermo is closed …?

Video includes 4-segments, all taken through one heat cycle of the coolant.

Segment 1
Video begins with coolant hot (200⁰F +), thermostat open, both radiator fans running.

At one point when the fans kick off when temp is still high (must consider the temp reading is coming from neck of radiator, not the thermo-housing where the fan sensor is located) indicating maybe coolant void at fan sensor - possibly from lack of flow-pressure pushing coolant up to elevation of fan sensor/thermo housing …) or maybe a flow restriction in the lower radiator hose (replacement hose in hand and next on install list). Lower hose felt good on the outside, but I realize the inner layers could possibly be delam potentially creating restrictions …
2012-7-2 Lower hose inspected (inner looked fine), hose was replaced and test run again with similar results.

Please take a look at the attached video sequence, let me know your thoughts on the amount of flow coming out the upper radiator hose (I would guess that an acceptable functioning water-pump in this car should be able to flow water more consistently to this 13” elevation …???

Spey

http://www.youtube.com/watch?v=UuWkTa-gH5Y&feature=plcp

Video after installation of new lower radiator hose (to eliminate the potential lower radiator hose was causing a flow restriction from interior delamination, etc.).

Test Results: Basically the same as previous water-pump test video illustration (just higher resolution video quality).

Question remains the same – does water-pump performance appear to be in line with acceptable?

tim73

That would be enough for me to swap out the water pump. Do you have a OBD2 tester capable of showing ECT temp? I would plug that in and watch it, if it gets warm and that bottom hose isnt scalding hot. Theyre not terribly expensive, just a few hours of work.

Spey

*? Like what kind of temps are we talking about (for EGT reading)?
Edit:
Sorry, I mis-read ... "ECT".
Help me out here, I want to use OBD2 tester to read the Engine Coolant Temp ...?
Does this mean that the computer (car) takes readings from the ECT sensor (the one located under the distributor), and I would use as a method of circumventing the interior gauge with a digital readout ...? Hmmm ..., new light on horizon ... please confirm for me. Additionally, if the senor location is under distributor it would seem that the temp measured here would be relatively consistent (slightly hotter yes) with the temp reading method I have used with digital-probe in the top of radiator return flow from engine. Guess I just need a little better understanding of how this temp location will help beyond previous tests I've done (thinking, thinking ... seems basically everything is confirming my original thoughts - H2O pump replacement)?

*? In your opinion, should the water-flow (at the 12-13" elevated height) be a consistent flow (at least during times when thermostat is open)??
I'm just not sure how much head-of-pressure a Honda pump should be capable of pushing ...?

From the beginning I was thinking water-pump replacement, but everywhere I read + my first hand experiences are that seals are what goes in a water pump (causes reduced pressure and eventual leaking thru weep holes). So I started asking around on a few forums for an effective method of testing, and got zippo feedback (so fashioned my own test scenario, but I have no baseline to measure results against ...). Always been cut & dry; water pump not so finicky about letting ya know it's life has expired.

*? Considering potential water-pump R&R in this Honda's future ... Does replacement of the timing belt require replacement of the tensioners and/or any other components?
I've read a few forums that say yes; other (non Hondas that I've done reuse of original tensioner was typical with timing belt replacement).

Appreciate any/all comments and constructive criticisms ...
Thanks,

tim73

Yeah, your engine has two temp sensors, one for the computer to look at(Your ECT sensor is very important, as it tells the computer what temp the engine is, and how much fuel it needs). The other sensor, is for the gauge on the dash. Normally, the one for the dash, is a smaller sensor in the head, while the ECT for the engine computer is located close to the thermostat.
My obd2 sensor can pull live data, things such as engine temp, dist advancement, O2 status(Closed circuit open circuit) engine rpm's etc

Ive only did a flow test one other time, and that was a f250 diesel. It was steady, but it wasnt enough. the pump turned out to be bad. Some times, the impeller just wears out or the casing, and all it is doing is cavitating, and not pumping the proper flow.

If the timing belt only has 40K on it, i would just look at it real good and reuse it. Theyre rated for 100K.

Spey

tim73, Thanks for reply:
Looks like on the Honda VTec engine both the ECT Sensor & the Dash Gauge Sensor are in the cylinder head below the distributor (thanks for your insight, I wondered what that second sensor with the multiple wires, vs. single wire on the gauge sensor, was for - ECT to computer). Will give the timing -belt a good look over and try to better confirm maint. record on last replacement mileage (but really leaning towards T.B. replacement if the cover need to come off for the water-pump, but question related to tensioners still).

**? Anybody know the answer to:
"... water-pump R&R in this Honda's future ... Does replacement of the timing belt require replacement of the tensioners and/or any other components?"

Regards,

Spey

2012-7-4 New Water Pump (impeller vanes were corroded badly and partially missing) Flow improved greatly.

Now that the flow has been greatly increased, will perform another Combustion Gas Test in the next few days to confirm (hopefully) no combustion gas leaks into the cooling system, and then a chemical system flush and R&R of the coolant (new coolant is already dirty from the increased flow from the new water-pump).

doctorbee

Corroded pump means you should flush the cooling system as well.who knows how long the coolant was in there before all of this