QuestionQUESTION: Hello, Mr. Slater,
This is Ryan again. I installed the thermostat and replaced the upper radiator hose as you recommended. I tried the steps you wrote. I test-drove for about 6 miles. I let it cool down and when I release the bleeder valve, I hear hissing sound and the smell of burning gas from the valve. I check the oil dipstick and the oil cap to see whether there is any white residue in there. I did not find any. Should I be worried? I read on your website somewhere that if there is combustion gas in the radiator, it could be the head gasket busted? Is there a way to ascertain if it is the case? Please let me know. Thank you for your help and expertise.
Regards,
Ryan
ANSWER: Ryan, If you have a large combustion leak into the cooling system then you will see bubbles in the cooling system. Yes you can use a CO2 combustion leak Snap On, Mac, Matco tools. Maybe Napa auto parts? Check you Auxiliary fan for proper operation. I would run the car in park at 2500RPM (with someone in the car operating the throttle and looking at temp gauge.) Get the car hot and make sure you don't have any external leaks. Check that the Aux fan comes on and then when the engine gets hotter the Mechanical fan clutch should engage an you will feel a torent of air (loud) from the fan clutch. My bet would be the Aux fan is working intermitently or not at all.
-Evan
---------- FOLLOW-UP ----------
QUESTION: Hello, Mr. Slater,
I check the auxillary fan and it worked fine. With A/C on, I step on the gas pedal to bet. 2.5k and 3k for 15 minutes as you recommended. The thing is after the test drive, the auxillary fan is still on and I have to unplugged it to keep it from draining the battery. Is there a way to reset the auxillary fan to be operating normal. Can you recommend the best way to bleed air out of the cooling system? Or do I have to drive a few miles, cool it down and bleed again and again? Thank you so much for all your help. I greatly appreciate it.
ANSWER: If Aux fan is staying on then replace it, the final stage module is shorting internally. After the car has been idleing for a while with the A/C off the engine should cool off and the fan should stop. Only other possibility is the outlet radiator temp sensor sending an improper signal to the DME. Sensor is in the lower radiator hose. Cooling system should bleed itself after several heat cycles and topping off coolant when engine is cold.
-Evan
---------- FOLLOW-UP ----------
QUESTION: Hello, Mr. Slater,
I saw bubbles in the cooling system. I did the block test and the test turns positive (yellow). Is the fan switch in the lower radiator hose the same as the outlet radiator temp sensor. If it is, I am going to replace it. My car is manual transmission and the previous owner modified the air intake system with DINAN high flow cold air intake system. I look for the mechanical fan clutch as you've said but I could not find it in front of the water pump pulley. Could it be that it was removed during modification or it is not there because it is manual transmission? Since the block test is positive, what would you recommend I change? Should I just change the cylinder head gasket and head bolt set or should I change more? Thank you so much for your time and help.
Regards,
Ryan
AnswerRyan, fan switch is lower radiator hose/Rad. Outlet temp sensor. All the same two wire sensor. The fan blades bolt to the Aluminum mechanical fan clutch with three allen bolts. The fan clutch then screws onto the waterpump threads just in front of the water pump pulley. If you don't have a mechanical fan then you don't have a fan clutch. If you do have a mech. fan then the center aluminum portion of the fan is the clutch. I would get a Head gasket kit with out head gasket (sounds funny I know). This will get you all the neccesary gaskets. You need Proper repair instructions and Camshaft fixture blocks to properly set Cam timing. Only attempt this job if you are well versed in cylinder head repairs and have a significant amount of tools. This job is not easy and requires Advanced skill. What NEEDS to be done before any cylinder head repair is attemped is the valve cover needs to be removed and the cylinder head bolts need to be released and retorqued to factory spec (40Nm +90degrees +90degrees). To see if the threads in the Engine Block will hold and have not been structurally damaged in the overheat. If the threads strip out then a complete long block will be needed or a short block if the Head is still good. If Block is good and straight (less than 0.05mm warpage) then send the cylinder head out to a reputable machine shop and have checked for straightness, Pressure checked, and Zyglo checked for cracks. Maximum Machining limit on the cylinder head is 0.3mm. Cylinder head height stock is 140mm and machined should be 139.7mm. This is when you order your cylinder head gasket. You can order stock thickness or 0.3mm thicker to maintain stock compression. You are correct in replacing the Headbolts. Change oil and flush coolant to prevent cross contamination of fluids.
-Evan
