Hi all
We have been reading/searching this site for days and I have finally decided to post my question as we have had no fewer than 5 mechanics (including the Honda dealership) absolutely stymied by our problem.....
1999 EX 185,000 kms. (Canada)
No problems at all with the van except the failed tranny 2 weeks into ownership 6 months ago at 176,500 km (yikes!) Last week my husband installed a new timing belt, tensioner and pulley, water pump (brand new), thermostat, p/s and serpentine belts and serpentine tensioner. All from NAPA, all aftermarket parts. Everything went pretty much like clockwork.
We refilled the coolant and ran through the Service Manuals instructions for reving the engine at 1500 rpm in 5 min. intervals alternating between cold and hot etc. The only thing we did wrong, in our ignorance, was perform this with the rad cap ON. Heat blew nice in hot in both front and rear of the vehicle, engine temp on dash gauge was normal. No problems. (or so we thought). 2 days later, as I was driving on the highway the heater gauge started to climb from just above mid-point to the red area as I approached my home. I slowed right down, turned a/c off and went very slowly...
So, now we have had 4 mechanics (including the Honda dealership today) and a 5th over the phone looking at our vehicle. The thermostat had been changed back to OEM with no improvement, we have tried 'bleeding' the system for countless hours....and now have finally removed the thermostat to try to find out WHY the top rad hose is consistently 40 degrees hotter than the bottom (and why the coolant wants to boil out of it when it's open).
With the thermostat installed, the top hose would reach 195-198 before it would drop at all, would only drop 10-15 degrees and the bottom hose never comes up above 155. The coolant would back out of the radiator into the large funnel and then eventually start boiling. We even installed a bleeder on the back top heater hose, checked for coolant flow to it (no problem), but the hose temps are a mystery and the van starts to overheat shortly after the rad cap is on even at an idle.
It's not the temp sensor, as he used a paperclip to create a continuous circuit and keep the fans both on (advice of non-honda mechanic), and the hoses are giving the same temp differentials with the thermostat OUT of the housing (that is, slightly cooler but still 40 degrees difference). Temps only ever reach 102 on all rear heater hoses, while the top rad hose off engine reaches as high as 198 (and if you check bleeder on back, there's fluid there).
Is the new water pump bad, do we have an extremely bad airlock (the entire system has now been drained and refilled 3 times), a possible physical block in the system somewhere, small leak, or .... eghads.....a failing head gasket? None of the mechanics think it's the head - there are no other signs of it, and the van never overheated to the point of steam etc. Just hit the red line that one time on the way home the other day.
It is now parked outside a different mechanic's shop with an extremely good reputation (the one giving us advice over the phone) awaiting monday morning. Honda was pretty much useless - including saying they couldn't change the oil for us as the bolt was on too tight! (Need a new $250 oil pan.....hmmmm....). $200 later in towing and diagnostics and we're no farther ahead (and 3 kids wondering when we can go to Disneyland!)
I think I'll ask for a pressure test first thing to rule out head gasket leak or other leak. Any thoughts/advice would be GREATLY appreciated. We've had this big holiday planned for months and are supposed to head out in the morning here. Not going to happen, and, like I say, we've been working on this for days!!!!!
Sorry for the long post - hoping someone has got advice, and that maybe someone else can benefit from it at some point too!
Thanks so much.
Bonnie
We have been reading/searching this site for days and I have finally decided to post my question as we have had no fewer than 5 mechanics (including the Honda dealership) absolutely stymied by our problem.....
1999 EX 185,000 kms. (Canada)
No problems at all with the van except the failed tranny 2 weeks into ownership 6 months ago at 176,500 km (yikes!) Last week my husband installed a new timing belt, tensioner and pulley, water pump (brand new), thermostat, p/s and serpentine belts and serpentine tensioner. All from NAPA, all aftermarket parts. Everything went pretty much like clockwork.
We refilled the coolant and ran through the Service Manuals instructions for reving the engine at 1500 rpm in 5 min. intervals alternating between cold and hot etc. The only thing we did wrong, in our ignorance, was perform this with the rad cap ON. Heat blew nice in hot in both front and rear of the vehicle, engine temp on dash gauge was normal. No problems. (or so we thought). 2 days later, as I was driving on the highway the heater gauge started to climb from just above mid-point to the red area as I approached my home. I slowed right down, turned a/c off and went very slowly...
So, now we have had 4 mechanics (including the Honda dealership today) and a 5th over the phone looking at our vehicle. The thermostat had been changed back to OEM with no improvement, we have tried 'bleeding' the system for countless hours....and now have finally removed the thermostat to try to find out WHY the top rad hose is consistently 40 degrees hotter than the bottom (and why the coolant wants to boil out of it when it's open).
With the thermostat installed, the top hose would reach 195-198 before it would drop at all, would only drop 10-15 degrees and the bottom hose never comes up above 155. The coolant would back out of the radiator into the large funnel and then eventually start boiling. We even installed a bleeder on the back top heater hose, checked for coolant flow to it (no problem), but the hose temps are a mystery and the van starts to overheat shortly after the rad cap is on even at an idle.
It's not the temp sensor, as he used a paperclip to create a continuous circuit and keep the fans both on (advice of non-honda mechanic), and the hoses are giving the same temp differentials with the thermostat OUT of the housing (that is, slightly cooler but still 40 degrees difference). Temps only ever reach 102 on all rear heater hoses, while the top rad hose off engine reaches as high as 198 (and if you check bleeder on back, there's fluid there).
Is the new water pump bad, do we have an extremely bad airlock (the entire system has now been drained and refilled 3 times), a possible physical block in the system somewhere, small leak, or .... eghads.....a failing head gasket? None of the mechanics think it's the head - there are no other signs of it, and the van never overheated to the point of steam etc. Just hit the red line that one time on the way home the other day.
It is now parked outside a different mechanic's shop with an extremely good reputation (the one giving us advice over the phone) awaiting monday morning. Honda was pretty much useless - including saying they couldn't change the oil for us as the bolt was on too tight! (Need a new $250 oil pan.....hmmmm....). $200 later in towing and diagnostics and we're no farther ahead (and 3 kids wondering when we can go to Disneyland!)
I think I'll ask for a pressure test first thing to rule out head gasket leak or other leak. Any thoughts/advice would be GREATLY appreciated. We've had this big holiday planned for months and are supposed to head out in the morning here. Not going to happen, and, like I say, we've been working on this for days!!!!!
Sorry for the long post - hoping someone has got advice, and that maybe someone else can benefit from it at some point too!
Thanks so much.
Bonnie