Warm Starting Problem

[Guest blakec]

I just bought a 1992 Pathfinder XE 6 Cyl. 5 Speed and it was sitting for a quite a while not being run much. It just started having warm starting problems. I have found that when the engine is cool I can start the engine with out any problems but after it warms up it want s to die at low idle and it will not start up until it cools down. If I run cool water over the coolant sensor, or what I thin k is the coolant sensor, it will start up just fine.

 

I am not seeing any flow in the radiator . Is this a thermostat problem or a radiator problem?

 

I have read that it is best to get the thermostat from the dealer. Does this sound like the best solution to solving this problem?

 

Any recomendations would be helpfull.

 

-Blake

[Precise1]

Well, it definitely sounds sensor/electronic related... I recommend you run the ECU diagnostic routine first to see what it says. The directions are to be found in the Garage section under Tech Section at the top. Let us know what you find.

 

B

[SteveWA]

Had a problem like that in an old car. Oldsmobile. The ignition module was the cause, it would heat up and then the car would die. Cool down it'd run fine for awhile. I don't think the radiator/thermostate would cause it to die, it would just overheat.

[Guest blakec]

Well I ran the self diagnostics on the ECU and it returned a 55 code listing no fault if I did this correctly.

 

A bit more info that I did not share earlier...

 

I picked the car up about 40 miles away from my house. It was sitting for quite some time. The battery was shot and I had to buy a new one when I turned the car off to buy gas. The radiator at that time was really low. I filled it up with coolant and water and headed home. I was able to drive it just fine for two days and then one evening it started to sputter when accelerating. I let off the pedal and the RPM's dropped to below 250 and it stalled. I could not start it for a few mins. then it started. I made it home and there it would not start again.

 

The next day it started fine. I drove around the block a few times and when it warmed up it stalled again and would not start.

 

The next day again it did the same thing as the previous day. Starts fine when cold and then hard/no starting when it warms up. I recalled that a collant sensor is very important for operations and the ECU so it knows what it needs to do. I ran a water hose over the thermostat housing where two sensors reside, assumed them to be coolant and temp not sure, and the radiator.

 

When it was cool it started right up. I let it warm up again and the same problem again. I then noticed that the top of the radiator was pretty hot while the bottom was cool. I assumed either coolant sensor , stuck closed thermostat, or clogged radiator.

 

A mechanic I know said it was the thermostat and to only buy one from the dealer. The thermostat looks pretty hard to get to.

 

This is where I am at at this point. I want to troubleshoot this and not throw parts at the problem.

 

-Blake

[88pathoffroad]

It's probably your ignition coil's power transistor. Mine did the exact same thing when it started to go out. Problem is, it costs like $100. Maybe try a junkyard?

[Slick]

If the Pathy had been sitting for a long time.. the gas in teh tank could have gone bad... therefor plugging the fuel filter or pump...

I know a 4.3 S-10 is only slightly similar to a Pathy.. but as my fuel pump was going out.. my S-10 was much harder to start when she was hot than when cold.

Edited August 9, 2005 by Slick

[94extreme]

hey, does a 4tech s-10 have one of them power transistor do hickies? i have the very same problem with the darn chevy.. hate to just throw money at it..

fuel pump is a suspect but when cool or moving it does run.. i do get spark when hot though..

[88pathoffroad]

I doubt it, but you never know.

 

Say, this isn't a starting problem like the thread title says, by the way. It's a dying-when-it-gets-hot problem.

[94extreme]

it's kind of both but the thing is that my truck doesn't really get hot but just a bit over normal operating temps.. if you're refering to my post.

[Slick]

just over normal temps? check yer radiator level.. like my Pathy.. if she ain't full... she lets me know!

[Guest blakec]

I did some thinking on this and came up with that the thermostat was stuck and that the coolant sensor was reporting high temps so the ECU was protecting the engine by trying to shut it down.

 

I had no idea if the ECU would do this but anyway...

 

I replaced the thermostat and refilled the system. It no longer tries to stall and it has no more problems starting when warm. The coolant flow seems a bit low to me so I may replace the water pump to be sure that I am not cooking the engine. The radiator is now showing signs of heat in the middle and some at the bottom of the radiator. I think it should be warmer than what it is at the bottom making me think the flow is not good.

 

Any commentary about waterpump flow? Should it be really visible at the top of the radiator?

 

-Blake

[88pathoffroad]

If it doesn't overheat or cause any more problems, I'd leave it be. If it ain't broke, don't fix it!

[Precise1]

I am not seeing any flow in the radiator . Is this a thermostat problem or a radiator problem?

 

That from the initial post I missed some how. Sorry. There should be some flow, but it is not always visible looking in the radiator cap for several reasons. While I doubt the ECU protects against overheating, it may affect things through the sensor readings.

I'm a big believer in what 88 said (ain't broke, don't fix). Unless you can determine something is an issue, leave it alone. What does your temp gauge read ? If you are worried about it, buy and install a coolant temp/oil temp and pressure gauge (one that registers in degrees, not arbitrary lines)... That is what I plan to do once I have income...

 

B

[88pathoffroad]

Oh, I meant to say...there's no safety shut-off set-up with the ECU. It'll overheat until it melts the pistons to the cylinder walls. Ask Pathfinder Phil about that sometime.