1990 Mustang GT - Supercharged Kenne Bell - 2.1
Well, for a while, I have been chasing gremlins in my 1990 Mustang GT. Spent numerous hours and dollars. Recently, I pulled the car off the road for the Winter after not driving it for 2 months. Been doing numerous diagnostic tests but was only finding a Code 91 and Code 12. I wanted to post an update since many do not follow through on their ordeals and how they solved them.
Ran a compression test and all cylinders were good and equal. Ran a KOER test (got the Code 91 & Code 12) and proceeded with the cylinder balance test on several occasions and always came up with a Code 9 (Pass). The last time I ran it, the plugs turned all black after being lean white for 2 months of testing. Prior, I had noted that plug #6 was not white but yellowish-orange on the center porcolean. Decided to do a leakdown test and I think I got around 6% - 8% leakdown on every cylinder. Need to build my own leakdown tester cuz I don't trust this harbor freight gauge. Anyway, I removed the thermostat and replaced the housing w/o the thermostat before doing a leakdown/pressure test. Had the pressure between 90-100 psi. I found that cylinder #2 would allow a few bubbles into the thermostat housing every 20 seconds. Continued on to cylinder #6 which I had suspected based on the plug color. I found this cylinder to be a bit more violent with the air bubbles coming out of the thermostat elbow coolant (top radiator hose removed) occuring every 4-5 seconds. Thus, I apparently have leaks in my head gaskets and they must be pulled and then heads checked etc. First note is that no problems showed up in the compression test, cylinder balance test, or leakdwon test numbers. The problem was only found once the thermostat was removed and the engine filled with coolant to 1/4 of an inch from the top of the thermostat housing. These same tests were performed last Spring (including a radiator pressure test) and nothing was found. This time, the thermostat was removed and any evidence of bubbling was visibly observed.
The car has not run right for about a year and a half. The last tow months, it would stall out when started and sensors were checked and checked/replaced. Though, most of the last year and a half, the car drove, seemed to purr but had a rough idle , down on power, and acted erratically. I am not sure if I have found everything. It could be leaking from one of these cylinders to another ... haven't checked that yet (not sure that I may) ... may also have leaky lower intake gaskets but they will be replaced anyway. I must still check a few other things like the oxygen sensor wiring due to the lean codes.
Was thinking going with the MLS Cometic gaskets this time due to the supercharger ... is there anything better out there??? Kenne Bell told me that they did not know of any head gasket problems on stock 5.0's blowing head gaskets with this kit ... apparently I am the first (yeah, right). I want to put the best head gaskets and intake manifold gaskets on this engine so I do not have to re-visit this problem or go through all of this again ... your suggestions would be most helpful if anyone has suggestions better than what I am aware of? Also, head gasket or intake adhesives for supercharged applications might also be helpful??? I have all Winter so i want to evaluate what the best route to take on solving this problem once and for all! Wanted to throw a set of AFR's on here but do not think my finances are going to allow it right now ... but will spare no expense on the gaskets etc.. oh, will not be O-ringing at this point either. thank you for your help and I hope this information helps many others out there!!! To run such time-consuming tests over and over and not have them show anything has been very time-consuming!!! But, fixing it is usually the easy part!
Well, for a while, I have been chasing gremlins in my 1990 Mustang GT. Spent numerous hours and dollars. Recently, I pulled the car off the road for the Winter after not driving it for 2 months. Been doing numerous diagnostic tests but was only finding a Code 91 and Code 12. I wanted to post an update since many do not follow through on their ordeals and how they solved them.
Ran a compression test and all cylinders were good and equal. Ran a KOER test (got the Code 91 & Code 12) and proceeded with the cylinder balance test on several occasions and always came up with a Code 9 (Pass). The last time I ran it, the plugs turned all black after being lean white for 2 months of testing. Prior, I had noted that plug #6 was not white but yellowish-orange on the center porcolean. Decided to do a leakdown test and I think I got around 6% - 8% leakdown on every cylinder. Need to build my own leakdown tester cuz I don't trust this harbor freight gauge. Anyway, I removed the thermostat and replaced the housing w/o the thermostat before doing a leakdown/pressure test. Had the pressure between 90-100 psi. I found that cylinder #2 would allow a few bubbles into the thermostat housing every 20 seconds. Continued on to cylinder #6 which I had suspected based on the plug color. I found this cylinder to be a bit more violent with the air bubbles coming out of the thermostat elbow coolant (top radiator hose removed) occuring every 4-5 seconds. Thus, I apparently have leaks in my head gaskets and they must be pulled and then heads checked etc. First note is that no problems showed up in the compression test, cylinder balance test, or leakdwon test numbers. The problem was only found once the thermostat was removed and the engine filled with coolant to 1/4 of an inch from the top of the thermostat housing. These same tests were performed last Spring (including a radiator pressure test) and nothing was found. This time, the thermostat was removed and any evidence of bubbling was visibly observed.
The car has not run right for about a year and a half. The last tow months, it would stall out when started and sensors were checked and checked/replaced. Though, most of the last year and a half, the car drove, seemed to purr but had a rough idle , down on power, and acted erratically. I am not sure if I have found everything. It could be leaking from one of these cylinders to another ... haven't checked that yet (not sure that I may) ... may also have leaky lower intake gaskets but they will be replaced anyway. I must still check a few other things like the oxygen sensor wiring due to the lean codes.
Was thinking going with the MLS Cometic gaskets this time due to the supercharger ... is there anything better out there??? Kenne Bell told me that they did not know of any head gasket problems on stock 5.0's blowing head gaskets with this kit ... apparently I am the first (yeah, right). I want to put the best head gaskets and intake manifold gaskets on this engine so I do not have to re-visit this problem or go through all of this again ... your suggestions would be most helpful if anyone has suggestions better than what I am aware of? Also, head gasket or intake adhesives for supercharged applications might also be helpful??? I have all Winter so i want to evaluate what the best route to take on solving this problem once and for all! Wanted to throw a set of AFR's on here but do not think my finances are going to allow it right now ... but will spare no expense on the gaskets etc.. oh, will not be O-ringing at this point either. thank you for your help and I hope this information helps many others out there!!! To run such time-consuming tests over and over and not have them show anything has been very time-consuming!!! But, fixing it is usually the easy part!
