STILL overheating, never been so frustrated in my life :(

have you checked the fans clutch and whether the coolant temp sensor is within spec?

 

Maybe shoot Baron a PM

He also has a thermo fan and an aluminium shroud, and has the same probs as you, although not as severe.

Sounds like the shroud and the thermo might me a restriction to the natural high airflow that is normally present over the radiator when you travel at speed.

 

Long shot!

The E.G.R. control valve controls the quantity of exhaust gas to be diverted to the intake manifold through vertical movement of a taper valve connected to the diaphragm. Vacuum is applied to the diaphragm in response to the opening of the throttle valve.

The solenoid valve responds to the ON/OFF signal from the E.C.U. When it is off, a vacuum signal from the throttle chamber is fed into the E.G.R. control valve. When the control unit sends an ON signal, the coil pulls the plunger downward and cuts the vacuum signal.
..................

If the diaphragm is perforated the egr could be stuck open, feeding the engine hot exhaust gas, which should be
going out the exhaust. This combined with higher than normal boost pressure can cause all sorts of problems. Ash from TTnet wrote quite a bit on this subject, he says if your egr is faulty, it can cause detonation and over heating, and recommends deleting it all together, which most people do. It?s a long shot I know, but worth checking.

The fact that your car over heats,and then is able to cool itself, shows that the cooling system is doing its job. My guess is your head gasket is leaking, and gets worse as the engine heats up. The engine may have been over heated before you brought it, imho!

 

Hydrocarbon tests are not reliable, I had mine done and came up fine even though every water jacket had blown through the head gasket.
Have you done a compression test??

 

I've tried fitting a stock clutch fan and removing the thermo with the same result. Only thing is I don't have a fan shroud to try but a few people who don't run shrouds have told me that they don't have any problems.

Ben

 

Worth a look see, do you know if datascan can tell me if the egr valve is operating correctly?

Ben

 

Datascan seems to read ok and corrosponds to what my aftermarket gauge is telling me so would this mean the CTS is ok?

Ben

 

No I haven't, but I guess it's definatly worth a try before tearing down the engine.

I'm a pretty handy with a set of tools so is this something I can try myself if I can buy/borrow a compression tester? Or is it a difficult test to get right which is what i'm led to believe after everything Big Baz went through?

Thanks
Ben

 

Data scan wont

help, you can do a manual check to see if its working.
Look in the manual EF&EC-11 and 12 for instruction, on how its done, very easy. Getting rid off the egr is a pain in the ass, but if its Faulty get rid off it. Have a look through this article by ash,
he explains it way better than i can.
http://www.twinturbo.net/net/viewmsg.aspx?forum=technical&msg_id=967920

 

Interesting dried coolant white

Sounds like you have had Chemi weld addative in your coolant system,which is for leaking head gaskets- at some stage.Chemi weld is notorious for causing blockages throughout the motor.Also get a chem check done on the coolant (not familiar will gas test)for exhaust gases,straight after you have given it a good flog.Thats my 2cents worth.

 

I've changed the coolant completly several times in the last few months so I know there are no addatives or anything else in there.

The test I had done was for exhaust gasses. (TK test I think he called it)
It was negative but as instructed but the mechanic I only drove the car straight there (about 2 klms) and it was barely warmed up so he could get the cap off with no pressure behind it. Maybe I should give it a reasonable hammering and have the test done again.

He showed me what should happen by holding the tester near the exhaust pipe and the liquid in it changed color pretty quickly.

Ben

 

ascension.. can understand your frustration.. 50 posts

and still no solution .. certainly unusual for this forum ... !!!

trust that something reveals all .. and soon ..!!!!

 

That EGR tech info was an interesting read, and it sparked the memory that I have removed all the egr solonoid and hose crap along with the aiv system etc. Funny thing is when I did this a few months ago I found that the line to the EGR valve had all ready been cut and plugged.

If I read the article correctly this means that with that line plugged and there for no vacuum operation, my EGR valve is relying only on it's internal spring to remain closed all the time. If this is the case and the spring happens to be faulty or the valve is not sealing properly this could lead to an unknown amount of exhaust gas re-circulating back to the intake system and upping the engine temp.

So does this sound plausible and fit my symptoms?
And if so how would I go about checking/testing?

Regards
Ben

PS, Thanks for the support Black Baz, I hope your right

 

Datascan will only tell you if the ECU is

turning n and off the EGR solenoid... but the EGR itself could be stuck open/closed/partially open etc.

Are the egr pipes which go into the plenum blanked off? Thats the easiest way to eliminate any problems the EGR might be giving.

 

I'll check it out, after I find a picture or something to show me what i'm looking for.

Thanks, and merry xmas to everyone.

Ben

 

Hey, just been reading about the EGR operation and found this section.

"Too much EGR flow will result in poor fuel economy, rough running and increased emissions. Too little flow can possibly cause internal engine damage from overheating"

So if my valve is stuck open would this actually reduce engine temps?

Ben

 

???

EGR VALVE?

I dun have one of those!

I guess mine will over heat? (WOT A LOAD OF BS!!!!!)

 

Yeah it sounded a bit suspect to me but it was from a tech article not some nissan propaganda so I wasen't sure what to believe.

Anyway, I intend to remove it all so does that require a plenum pull?

Ben

 

I did a temporary EGR bypass with plenum on by cutting the pipes leading into the plenum and blocking them with quick steel, there should be a guide on twinturbo.net.

 

I removed the FMIC today and went for a run. Pretty cold overcast day and on the freeway temp sat around 90, going up to 95 on an incline.

So looks like removing it has helped somewhat but is not the cause. This is what I expected since plenty of people are running front intercoolers without dramas.

I drove back home through residential areas, quite hilly and plenty of stop/start action. Temp still stayed around 90 but on hills, even VERY short ones temp would still spike 5-8 degrees in a matter of seconds.

Still sounds to me like head gasket. I'll go get another test done at a different mechanic for my own peace of mind.

Does anyone know if the hydro carbon test can indicate ok but there still be a leak?

Best wishes for the new year everyone
Ben