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2005 Maxima overheats only when idling but engine temp comes down immediately if I rev up the engine (even though car is stationary)
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kedarp
New User
Oct 5, 2024, 11:13 AM
Post #1 of 6
(365 views)
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2005 Maxima overheats only when idling but engine temp comes down immediately if I rev up the engine (even though car is stationary)
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hello everyone,
I own a 2005 Nissan Maxima that I was driving from Illinois to California, a 2000 mile journey over a 5 day trip.
A 1000 miles into the journey, at Rawlins, Wyoming, I felt a light smell of coolant in the passenger cabin and decided to bypass the heater core with a bypass kit. I did the job myself.
1. After driving for 280 miles from Rawlins to Utah (it was very hot outside), the car suddenly started to overheat when going downhill.
2. I had introduced an air bubble when I bypassed the heater core at Rawlins and had never bled the coolant circuit. In any case, I parked the car for 30 mins when going downhill and it cooled down.
3. Thereafter, after every 15 miles or so, the car overheated regularly, especially at lower rpms.
4. If I raise the rpm of the car (even when stationary) to 5000 rpm, the temperature gauge immediately comes down.
5. I have no coolant leak and the coolant level never changes.
6. The radiator is new'ish and has only 3000 miles on it. The radiator passes a pressure test at 15 & even 20 psi.
7. The engine oil was not milky or frothy. There is no white smoke coming out of the exhaust either.
8. I replaced the thermostat myself 2 days ago, so it has a brand new thermostat but the overheating problem persists.
9. Both the radiator fans work at both high and low speeds and come on when the engine starts to overheat. The radiator fins are not blocked either.
9. I noticed that the radiator top (inlet) pipe gets very hot when the car is overheating but the bottom (outlet) pipe is stone cold to the touch.
10. I ran the engine for 10 mins at idling with radiator cap removed to eliminate any air pockets.
11. Even when the coolant level is full, I don't see a lot of coolant entering the radiator at lower rpms and it does increase at higher rpms but I suspect the flow is still quite poor. I have attached a video of the coolant flow (after removing the coolant pipe at top of radiator). The engine was initially at 800 rpm and later at 5000 rpm.
12. I disconnected the heater core inlet hose (tried both inlet and outlet hoses) to see if coolant comes out of the heater core inlet hose with force. But even at 5000 rpm, there is no coolant trying to leave the heater core inlet hose. My car always had a problem getting the inside to heat -- it was *extremely* weak
Mechanic shop responses so far:
1. The first mechanic shop quoted me $1000 to change the radiator but when I asked him to show result of pressure test, it passed.
2. I asked the second mechanic shop to replace the water pump and was quoted $1074 for the job. When I took the car to them, I was told it's a blown head gasket and was quoted $4700 for the job. He was not able to explain why raising the engine rpm cools the engine if the head gasket is blown. Also there's no "smoke" in tailpipe and the engine oil is clean.
Thanks for reading ! Appreciate all help and answers.
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kedarp
New User
Oct 5, 2024, 4:54 PM
Post #3 of 6
(350 views)
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Re: 2005 Maxima overheats only when idling but engine temp comes down immediately if I rev up the engine (even though car is stationary)
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Thanks for the response Hammer. Can you also please comment on whether the flow of the coolant seem typical of a good water pump to you at both rpms ?
(This post was edited by kedarp on Oct 5, 2024, 4:55 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 5, 2024, 5:15 PM
Post #4 of 6
(347 views)
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Re: 2005 Maxima overheats only when idling but engine temp comes down immediately if I rev up the engine (even though car is stationary)
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There really any good way to test for that. You could remove the upper hose from the radiator and rev the engine for a few seconds but if the thermostat is closed at the time you will get nothing.
The only way would be to get a piece of clear radiator hose if they even make such a thing. You might be able to do it with the heater hoses.
It's a difficult and risky job to change the water pump as it is driven by the timing chain and you risk jumping time.
I'd bet anything that you haven't gotten all the air out of the system. It can be difficult. We do it by putting the system under vacuum and sucking the coolant in.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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kedarp
New User
Oct 5, 2024, 6:30 PM
Post #5 of 6
(338 views)
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Re: 2005 Maxima overheats only when idling but engine temp comes down immediately if I rev up the engine (even though car is stationary)
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I did the experiment with the heater hose. It did not have any coolant flowing out of it even when the radiator was full with coolant and at both idling and 5000 rpm.
I tested with both inlet and outlet heater hoses just in case I mistook the heater core inlet hose for the outlet hose.
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 5, 2024, 6:42 PM
Post #6 of 6
(336 views)
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Re: 2005 Maxima overheats only when idling but engine temp comes down immediately if I rev up the engine (even though car is stationary)
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If you have air in the system those tests won't work. Just because the radiator is full means nothing.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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