Second Generation Nissan Xterra Forums banner

1 - 20 of 37 Posts

·
Registered
Joined
·
18 Posts
Discussion Starter #1
So I've been noticing any issue of my temperature gauge almost reaching the H segment while idling in traffic. It was reading at 116C+ (240F) on the ECT at these points. I took it into the shop, who replaced my radiator cap and thermostat but said that due to the heater core bypass, the coolant is not able to circulate. I opted to forego testing it with a new hose assembly as I'm assuming the heater core was bypassed due to failing/leaking (I bought it as is). The operating temperature now looks like it stays around 106C (222F) now (IAT 53C). Is this a normal thing with this bypass?
 

·
Registered
Joined
·
128 Posts
Honestly, I doubt the bypass has much to do with it. My experience has been that aftermarket thermostats are junk. I had a high temp issue (very similar to what you are describing) and I solved it by replacing the thermostat with a Nissan branded thermostat.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #3 (Edited)
Honestly, I doubt the bypass has much to do with it. My experience has been that aftermarket thermostats are junk. I had a high temp issue (very similar to what you are describing) and I solved it by replacing the thermostat with a Nissan branded thermostat.
The thermostat was replaced by an OEM. They told me that since the lines aren't going through the heater core, it can't maintain pressure causing the coolant to not be circulated. When they tested the coolant before flushing it, it was almost brown/red on the test strip so I'm assuming it's just boiling? Nissan just replaced the coolant about 2 months ago. So far it's staying at the middle part of the temperature flag at it's hottest (So far) so maybe I'm just being paranoid..
 

·
Registered
Joined
·
409 Posts
If the heater core was bypassed correctly, the flow thru the engine would not be reduced. Our coolant should be green. Brown/red is not right but Nissan did the coolant change? Hope you find a shop that can figure out what is the problem.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #5
If the heater core was bypassed correctly, the flow thru the engine would not be reduced. Our coolant should be green. Brown/red is not right but Nissan did the coolant change? Hope you find a shop that can figure out what is the problem.
A muffler shop had put in orange coolant before I took it in to Nissan, and Nissan said WTF drained it and put in green. Maybe the remnants of the orange coolant discolored it. I'll probably just take it into Nissan to see if they can figure it out, I'm not exactly sure how this bypass was supposed to be done but nothing is connected to either port for the heater core and it's just a straight line going right past it.
 

·
Registered
Joined
·
409 Posts
I doubt the remaining orange coolant would be enough to make green coolant look brown/red. If the Heater bypass line is going right across Near the heater, it is probably ok. If you take your X to a dealer, they will demand to replace the heater before anything else.
 

·
Registered
Joined
·
1,377 Posts
Im wondering if your mechanic used a coupler in the line which may be restrictive.
 

·
Registered
Joined
·
1,469 Posts
So I ran with my heater core bypassed for months - in south carolina - in the summer - without issue.

However if the bypass is not done correctly - you could have issues. All you need to do is connect the two heater hoses that normally go in and out of the core together - I think you need a 3/4 inch hose coupler. If someone did something other than that, like plugging one or whatever I can see it not working.

Orange + green = brown. Skip all stealers, go to lowes / HD and buy a 3/4 hose coupling and connect the two hoses properly, then drain all the coolant and replace with new coolant of your choice - and see what happens. Will cost you likely less than 30 bucks and an hours worth of time.
 

·
Registered
Joined
·
2,457 Posts
The thermostat was replaced by an OEM. They told me that since the lines aren't going through the heater core, it can't maintain pressure causing the coolant to not be circulated. When they tested the coolant before flushing it, it was almost brown/red on the test strip so I'm assuming it's just boiling? Nissan just replaced the coolant about 2 months ago. So far it's staying at the middle part of the temperature flag at it's hottest (So far) so maybe I'm just being paranoid..
The different types of cooling might be causing the discoloring, but it could also possibly be the radiator cross-contamination that's occurring, which no one mentioned. If you you're still getting discolored coolant after you swap again, I'd strongly urge you to drain the trans fluid and see what it looks like. If it looks like it's contaminated with coolant or if you get a strawberry milkshake look in your coolant reservoir, your radiator has failed. You'll need to bypass the trans cooler or install a new radiator.

Another thing I didn't see mentioned, was the radiator cap. The cap on the rad should have no spring, the cap with the spring goes on the coolant reservoir. Are your caps in the correct spot?
 

·
Registered
Joined
·
1,811 Posts
couple of thoughts:

rikrong had some good ones as well..

1. if nissan did a coolant flush a few months ago I would take it back to them and just tell them that they flushed the coolant a little while ago and now its running hot.. they should take a look at it and make sure they didnt screw something up and probably figure out what is wrong in general.

2. the coolant may be becoming contaminated from the radiator trans cooler leaking. even if the rad is bypassed so that the trans is safe from smod, here could still be some atf in the rad trans cooler, that is now leaking into the coolant. or it could just be a mix of orange/ green coolant.

3. if the bypass was done right it shouldnt impede flow of coolant.

4. I'd do what idn888 suggested and see what happens next.

5. let us know how it works out!
 

·
Registered
Joined
·
10 Posts
Hello everyone. I am having the same problem with my X and I think that it could be the bypass. I did the bypass using the original hose part that goes into the heater core because it had all the connections to the reserve tank and the other cooling system parts. I am thinking on removing that and creating the bypass from scratch using Home depot parts and see if that fixes the problem. The first time that I did it, i though the problem was that the connections was higher than the cap of the radiator and that created an air trap. I since then lowered to be lower than the radiator cap but the overheating still continues. Idle temp is at 221* F. If I let it sit for like 2 to 3 minutes and I rev the engine to 2K RPM the temp drops to 213* and even 210*. Someone told me in another forum that it could be overfilled with coolant and that is creating the low flow in the system. ( I have to try that one) I will try to keep you posted on this tread but if anyone finds a solution before please share it as I am going nuts! I have replaced the Thermostat, the fan clutch and the Radiator so far and nothing improves! The only thing left to replace is the water pump!. Does anyone have any Idea on how to test the water pump?
Thank you
 

·
Registered
Joined
·
10 Posts
I was thinking that too a while back but here is the thing..... I turn on the truck and let it Idle until it gets to the 221* that is running at.I won't rev it or anything. just idle. Once it gets there I let cool down completely. I will comeback the next day when is cold and open the Radiator cap and the system is full of pressure, and the coolant gushes out along with some air until the pressure is released. I read somewhere that the pressure is supposed to be sucked back into the engine when it cools down but for whatever reason my truck is not doing it. It also shows that the system is holding pressure so there is not a blown HG.
 

·
Registered
Joined
·
409 Posts
I replaced all the plastic hose connectors (T’s, etc) in that area with brass home depot stuff so I can’t see how by passing the heater is causing the engine to run hotter. Must something else.
 

·
Registered
Joined
·
1,469 Posts
I was thinking that too a while back but here is the thing..... I turn on the truck and let it Idle until it gets to the 221* that is running at.I won't rev it or anything. just idle. Once it gets there I let cool down completely. I will comeback the next day when is cold and open the Radiator cap and the system is full of pressure, and the coolant gushes out along with some air until the pressure is released. I read somewhere that the pressure is supposed to be sucked back into the engine when it cools down but for whatever reason my truck is not doing it. It also shows that the system is holding pressure so there is not a blown HG.
Do you have your pressure caps on the right locations - the one with the spring goes on the degas bottle - and the one without spring goes on the radiator itself. If that doesn't help get new rad caps. If you still have pressure on the system a day later and its still pressurized there is something wrong with your caps.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #18
I got it back from Nissan today. The service advisor assured me the heater hoses were going to be set up in bypass again because I told her I was pretty sure it was bypassed because of a failed heater core, but then I got it back like this...

Before:
124999
124998

After:
124996
124997


The ECT reads at 109C, so 3C higher than before at operating temperature so I'm not sure what to take from this. Heater core isn't leaking so that's good I guess, and I have heat now so that's cool too. The service advisor says it's not overheating anymore, but I don't think 109C (228F) is normal... but what do I know.
 
1 - 20 of 37 Posts
Top