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Engine Gets Hot During Uphill/WOT

Discussion in 'General Tech and Maintenance' started by edunnett, Aug 6, 2004.

  1. edunnett

    edunnett Junior Member

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    I recently purchased an '86 Civic Wagon 1500 MT. I don't recall it getting hot when we first bought it but now, after a lot of maint work, the temp gauge gets too close to the "H" for my comfort when I'm going up hills (WOT). It gets about 75% of the way to "H" when going up a hill for more than 10 seconds. It will drop back to 50% to "H" within 30 seconds of cresting the hill. I notice no other symptoms that seem related... other than the A/C can stall the engine at idle but I think that's the idle up solenoid... It seemed to run fine when we got it, except that it stalled at idle when the engine was cold - so that's what a majority of the tuning by my mechanic was centered around.

    I have had the following work done:
    - adjusted idle from 1200 to 900 rpm
    - replaced thermo, water pump, timing belt, fan motor (and switch), water hoses
    - mechanic did some work on carb to get the stalling at cold to stop - now i have a fast idle, mid-range idle and curb idle setting - ahhhhhhh
    - inspected distrib and replaced vacuum advance component
    - replaced spark plugs with proper nippon densos
    - replaced plug wires with some after market ones
    - new air filter, aux fuel filter, pcv filter
    - changed oil and filter

    Since noticing the overheating, I checked the timing with only an inductive timing light and adjusted to line up the marks - this had no effect on heat going up hills. I also found two vacuum hoses that were not connected properly (thanks to my mechanic I think) and found their home via underhood diagram. Car still behaves the same on the up hills.

    I feel confident that the cooling system is up to snuff - the only thing not new and recently adjusted is the radiator itself. I'm suspecting a vacuum leak someplace or possibly the timing under load? But the hood only gives me initial timing setting of 20 +/_ 2. I'm getting a vacuum gauge soon so will check against that but any other suggestions on what to check? This overheating going up hills is my only symptom. Other than that, the car cools on the downhills and keeps on chuggin. Also wondering if it's safe to drive it when the gauge reads that hot (75% to "H") or do I risk blowing a head gasket even in that range? Should I go after a new temp sender unit to be sure?


    PS - (added later same day) Noticed that during normal city driving after several minutes the heat creeps up here too. The cooling fan motor is running. A/C is also associated with another fan which runs when called upon. RPM seem normal for the type of driving. Ambient temp around 75 F. I'm suspecting either air in the system or faulty wiring (maybe some crossed current or lack of ground that's only apparent when fan kicks on or cylinders are firing faster?) now and POSSIBLY vacuum leak. Anyone tend to agree/disagree based on symptoms?
    Thanks for any help!
    Elissa
     
  2. B16

    B16 Super Moderator VIP

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    i was thinking timing was too advanced and raising temps, but that does not seem to be the case. did you bleed the cooling system when refilling it? possibly you have air bubbles trapped in it. not sure how to bleed the system on that ol car :) but some have a bleed screw near the thermostat. otherwise you can let the car idle with the radiator cap off until the fan switches on, while keeping an eye on the fluid level.
     
  3. edunnett

    edunnett Junior Member

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    RE: Timing - The timing was somewhat retarded when I first noticed the hot uphill problem. I had knocking and pinging on WOT/uphill then also. So I advanced the timing to spec and the K/P went away but the heat remained. :-(

    RE: Bleed/Burp the Cooling System - that was actually my first inclination that there was some air trapped in the system... So I burped it but no air bubbles were apparent. Perhaps I did not burp it thouroughly, and I did not rebleed it (only burped for a few minutes until the top hose got warm) after it came home from the shop. I can try that again but more completely this time.

    Will reply if that helps.
    elissa
     
  4. nfn15037

    nfn15037 Senior Member

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    This is my guess. It's an old car, try throwing a new radiator in it.
     
  5. B16

    B16 Super Moderator VIP

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    i didn't even see that part, yes get a new radiator for sure.
     
  6. edunnett

    edunnett Junior Member

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    Thanks for the responses! I will consider the new radiator possibly, but, before I spend a few hundred on parts, shipping and possibly labor on a new radiator, what might be symptoms of a bad radiator that I should look for? Overheating of course, but overheating is a symptom for a myriad of problems. Are there any more definitive tests I could try? I've drained and refilled it and only got a small amount of sediment the first time, no rust, coolant was clear - it's not showing signs of deterioration that I can see from the outside of the fluids inside. The car only runs hot (has not yet overheated) under WOT conditions then it cools right down within minutes. Is that a radiator-specific symptom? I'm also thinking the cooling system is working well in that the car has NOT overheated. What concerns me is something seems to be MAKING it hot under WOT. But I'm no mechanic... So I ask you kind people. :)
    Thanks again, and please keep the ideas coming! I'm burping the system tonight so will see if that makes a difference on Sunday when I next get to drive it.
    ELIssa
     
  7. asmallsol

    asmallsol Super Moderator

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    well first, disconnect the upper and lower hose, then take a hose and spray it in the upper hose to clean any gunk that has built up in it.. Then put the hoses back on and start filling with coolant (I prefer using premixed on tiny cars like civics) Once it reaches the top, keep the radiotor cap off, and turn the car on. Let it run until the car gets to full operating temp and the lower hose gets hot. Keep adding coolant when ever it goes down. Some times I try and "bounce" the car by pushing on the bumper so it shakes loose any air bubbles.

    also, if you find out it is the raditor, basicly the steps above will tell you exactly how to do a raditor change except you have to remove like 2 screws that hold it in and replace. Autozone, murrays, pepboys, ect will have replacement ones for around 100 bucks.
     
  8. edunnett

    edunnett Junior Member

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    This is curious - so I've burped the system about five times now... I have gotten the car to operating temp with the radiator cap off and the heat on, then let the car cool. I've then squeezed the top radiator hose to expell bubbles of air and all five times, air bubbles pop up... then I refill with more 50/50 mixture and burp more... I believe that the hot engine when driving up hills could be caused by air in the system but where could the air be coming from? I see no leaks under the car. I've gotten under it and looked, no leaks. Has new cooling system (other than radiator) so I suppose there were lots of opportunities to introduce air but is this normal, that it would be this gassy?!?!?! I've checked the hoses for tightness and it's been pressure tested fine. I also notice that the upper hose gets hot, and the lower hose is just warm - which seems the way the system is supposed to work. Any explanations for all the air? Reservoir tank is full to "max" but maybe the hoses aren't clamped on tight enough? I'll check that too....
    THanks
    elissa
     
  9. asmallsol

    asmallsol Super Moderator

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    Try waterwetter. Basicly how the stuff works is when water gets close to boiling, it starts to bubble and have air (like if you boil water in a pan, air will bubble from the bottom) with waterwetter, it makes it so when you boil it, the water just evaporates. This would keep gas from forming in the system.
     
  10. edunnett

    edunnett Junior Member

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    Well, I've tried burping the system several times now - always air in there. Tried water wetter, no difference. Tried a new coolant cap just in case, also no difference. *sigh* Now I have a vacuum gauge to try and diagnose if there's a vacuum leak someplace, maybe an EGR problem, exhaust back pressure....

    Now, if only I can figure out which of the hundreds of vacuum hoses might work best to hook this thing up to! :) I tried the two from the vacuum advance since they actually came off and the thermo-valve off the air intake but none of them had a good vacuum. I haven't gone through getting the air filter housing off yet to get at the other hoses down there though. I suppose that's the next step.

    Elissa
     
  11. MaaseyRacer

    MaaseyRacer Senior Member

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    As much as I was convinced that it was an air bubble, I am going to suggest that you try another thermostat. As recently my roommate bought a thermostat at NAPA, and it was crap! So we took it back bought another one put it in and it worked perfectly. Just a thought.
     
  12. 94RedSiGal

    94RedSiGal Senior Member

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    Well with my Si, I have now replaced my radiator and thermostat twice.... and at almost exactly five year intervals. For the first time, I was driving home along I-81 in VA, which is very hilly. I noticed that going uphill (and the hatch was heavily loaded up with my antiques) the temperature was rising above the normal level, then I would turn on the heat to lower it. And this was in the summertime. Anyway, I got home and once the radiator and thermostat was replaced, all was good. In terms of how that radiator looked, well there were tons of bugs and road crap imbedded in the fins and the was some green corrosion on the metal.

    When my second radiator went, it was a tiny coolant leak (that I kept an eye on for a few months) and green stuff on the metal. It also looked very tired. BUT this second radiator I replaced myself! I got one of those Koyo oem spec dual core ones for a Del Sol VTEC through 1-800 radiator for $130 (delivered to my door for free) and I think about $15 in hoses from Autozone. The thermostat was oem from the Honda dealership. It took me about 4 hours to do it, but actually I had to re-do the job the second day as actually I didn't replace the hoses the first day by ignorance and there was leakage. Use Honda radiator fluid also. It's free of silicates.

    So seeing as how you live in warm California and it's an older car, I would vote replacing your radiator and for maybe even doing the job yourself. Find a friend to wrench with. The hardest part for me was putting on the lower hose onto the radiator. But if I did it, anyone else can too. :)
     
  13. edunnett

    edunnett Junior Member

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    Well, the other day, I drained and refilled the current radiator to make sure it was bled and burped properly. Expelling the air didn't really make a difference though. Although driving with the heat on while going up hills really does help keep the temperature in check. I'm doing that for now.

    Another symptom I've noticed is that while my new Cooling Fan Motor and Cooling Fan Motor Switch appear to work (turns on sometimes while idling and any time when the A/C goes on) it doesn't ALWAYS go on when the temp gauge indicates that it should. My suspicion is that the radiator is in fact clogged and that the coolant at the bottom of the radiator isn't hot enough to trigger the fan & switch, yet the top of the engine block is hot enough to trigger the temp sensor.

    So, I've taken all your advice and purchased a new radiator from radiator.com for $130 including next day shipping. Figured the new radiator was actually cheaper than a re-core or a diagnosis, so what the hell. I'm guilty of throwing parts at the problem a little bit I think. I will be trying to install it this weekend. My only concern is that the new radiator has what appears to be a shallow scratch on the fins of about 6 inches long and only a couple millimeters deep if that. I'm not sure if that's a problem.

    Also, for those that have swapped the radiators before - I will have to remove it from the bottom of the car, and I'm not sure if I have the clearance when the car is up on ramps. I have to measure still but was that an issue for anyone?

    Thanks again!
    Elissa
     
  14. swanny

    swanny Senior Member

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    As long as the scratch hasnt cut into any of the cores you will be fine. Also you should pull the radiator from the top after disconnecting any wires for the fans/ coolant hoses etc.
     
  15. B16

    B16 Super Moderator VIP

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    it doesn't need to be too high off the ground since you can tilt the radiator to an angle to get it out from underneath. direct radiator swap is pretty straightforward. glad to hear you got a new one :)
     
  16. edunnett

    edunnett Junior Member

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    How would I know if the scratch cut into one of the cores? Would it leak? -elissa
     
  17. B16

    B16 Super Moderator VIP

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    yes, it would leak
     
  18. edunnett

    edunnett Junior Member

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    Good news. Bad news.

    Good news: I installed a new radiator over the weekend and it has greatly releived how hot the engine gets going up hills! Even the mother of all hills: a 10-15% grade that continues for about 3 miles, right after a 2 mile hill at 5% grade.

    Bad news: I still notice the temp gauge moving on those larger hills. Instead of ranging from 40% (0% being Cold and 100% being in the red) on the flats to 80% up those hills to 30% on the down hills in cooler weather it's still varying but not as much. Now it's 40% on the flats still, 45-50% on the big hills and 35% on the down hills. I figure that's not much to worry about but wanted to run it by you y'all. Also - and this is the part that's slightly troublesome, I live at the top of a 1/8 mile hill at approximately a 30% - it's STEEP. The car remained at 40-50% going up the hill, but upon cresting and turning into the driveway, it got hot, something like 60-65%. Any ideas?

    I'm thinking part of the equation might be the thermostat and/or temp sensor (the temp sensor is the only not new part in the cooling system now). I installed a new motor and new OEM fan motor switch which both work consistently. But they go on when the gauge is at 55% or so. The fan is on when I pull into the driveway and the temp crests at 55-60%. The thermostat aftermarket and is rated to open at 172 degrees but Honda thermos open at 180.

    I think I'm getting swings in temperature on the gauge because the thermostat is opening sooner than an OEM and the sensor is maybe becoming more sensitive to temp changes or is picking up voltage from someplace else and interpreting that as a temp change...?

    Whatever it may be, do you think there is any harm in watching it for a few months? Temp chages in those ranges shouldn't strain my head gasket or other parts, should they? Still getting great gas mileage though.

    Thanks again everyone! The car is definitely MUCH happier now thanks to your advice.

    Elissa
     
  19. driverunknown

    driverunknown Senior Member

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    did you bleed the cooling system after installing the new radiator?
     
  20. edunnett

    edunnett Junior Member

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    Yes, I should have mentioned that. I did a very thourough job of letting air from the system. I bled it as I filled it until no bubbles came out the bleed valve. Then I ran the engine with the radiator cap off until the fan went on 3 times and left it sitting there for about 20 hours while I periodically came by and burped air from the upper radiator hose. Eventually, after sitting overnight, it appeared there was no more air left. I suppose there still could be more in there but 20 hours of burping seems like it should do it. -elissa
     
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