Thread: Did the LIM this weekend, not getting full boost, and getting hot... wtf?

Question at the bottom...

About a month ago, I was driving home and the temp on my car ran up to about 240-250 deg.. Something way higher than the normal 180 operating temp. I pulled off the freeway as soon as I could. I got to a red light, and clouds of steam were coming from under the hood. I didn’t want to just sit at the red light, so I just took off and pulled into the gas station. I popped the hood, and the downpipe was literally on fire! Holly ****! So I blew it out and noticed that one of the heater hoses blew. Okay, so I know what the problem is, good.. But damn, its 12 midnight and I'm still 40 miles from home. The tear in the hose was about half an inch so I figured I’d just try to patch it so I could get home. I went into the gas station and bought some duct tape. Wrapped it around the hose a few times and filled the car with water. I took off, back onto the freeway and the car got really hot again. So I pulled over and tried to take a look at what was going on. Water was still leaking from my patch job. So I wrapped more tape to it, and traveled down the hose about 3 inches before and after the tear. Filled it back up with water, and got back on my way.. The temp stayed down at 180, and I booked it home. A few times along the way, the dummy light for Low Coolant came on. I assumed since the temp was still down at 180, I’ll push on. Got home and called it a night.
The next day I went out, bought new heater hoses and put them on. Filed the car back up with 50/50 dexcool and went on my way. No issues for a few days. Then, I got into a little sprint off a red light with a mustang gt, and noticed that my boost wasn’t going all the way over to full boost. I’d say it was only about 80%. ? I popped the hood when I got home again, and noticed a coolant leak from area around the water pump. After a bit more investigating, it looked like the water was coming from the LIM gasket between the block and the LIM. Weird place for it to be coming from. I guess it could have been that coolant bypass elbow too. I checked the oil with the dipstick, and its brown, not all milky, so it seems like no water is getting into the oil system. So I decided to replace the LIM Gasket since the car has 101k miles. I replaced the LIM gasket, the t-stat, the UIM gasket, the injector o-rings, and while I took the engine apart, I broke a vacuum line, so I fixed that too. Got everything back together, filled the car up with coolant, and took it for a test drive. Once I was up to normal operating temps, I decided to test the boost see if it was any better. Hit it WOT, and only about 40-50% boost. ? Then I went up a hill while I was on my test drive and while climbing the hill, the temp went to just above 210 again. That didn’t seem right, so I headed home. The temp went back to 180 when cruising around. I got home and after looking around on the forum, I found the issue with the boost. The lower nipple on the supercharger actuator was plugged. So I took the plug off, started the car and it immediately stalled. I tried it again, and then it fired up. I went for a test drive. 100% full boost. Hell yeah. That was last night. Today, I went for a drive and again, not getting 100% boost, maybe 80-90%. Sitting at a red light, the temp almost got to 210 again, and that’s with fresh gaskets, fresh coolant, new t-stat. I bled the cooling system when I filled it up, so I’m confused why I’m still getting hot, and not getting full boost.

So, here’s the question: What could be causing the car to still get warm while sitting, and what would be some reasons why the supercharger isn’t getting full boost? (going off the gauge on the DIC)

Well the things that come to mind are a vacuum leak somewhere. It could also be that you still have a coolant leak somewhere that is not allowing the system to pressurize completely.

What concerns me more, and I dont know what the possibility of it would be, is that maybe you have a blown head gasket or maybe one of the heads warped some from that temperature. Doesnt seem likely, but given all you have done I dont know I would rule it out at this point.

i would suspect that you did a faulty LIM job. its a pretty hard task to get it to seal properly if you dont know what youre doing.

can you do coolant system pressure test?

also your radiator might be clogged put your hand on it (carefully) check for cold spots
ive seen it where one half is hot and the other half is cold.

when you removed the S/C did you lose and/or replace the S/C fluid?

with the car running spray some carb cleaner around the LIM and see if you have a vacuum leak there

when you bled the system did you open that vent on t-stat housing, also did you turn on the heater on high?

Originally Posted by Bio248

i would suspect that you did a faulty LIM job. its a pretty hard task to get it to seal properly if you dont know what youre doing.

the hardest part in the install , is getting that plastic coolant elbow back on without breaking it (i always get a new one, because its cheap plastic that gets hot) i use some white grease and im golden

if you have an air pocket in the cooling system still you'll overheat, just turn the heater on and when its hot you should be fine there.

check your radiator though for cold spots, or a collapsed hose

go get a cooling system pressure tester, you can rent one, basically it goes in place of the radiator cap and you use this vacuum pump with a gauge , pressurize the system to 15 psi ( do not go over 15 psi) if the system holds at 15 psi then your ok, if it drops you have a leak in the system... do this test with the engine off of course

did you polug in the bbv and did you bleed the air out of the cooling system?

Sorry for not following up again. Anyway, ran the heater and that seemed to have fixed the over heating issue. I ran into a problem with the car stalling on start-up, and the car threw a P0440 code. EVAP system something or another. What ended up causing the issue was a vacuum leak on what I think is the EVAP Solenoid (back side of the engine, has a tube on one port, and a plug on the other?)... Once I got the port that was supposed to be plugged blocked again, the car runs great again. No issues to report. No codes, no over heating, no coolant leaks, nothing! HELL FRIGGEN YEAH!!!

Thanks again for all the help, and sorry for not following up sooner!!


Oh yeah, the supercharger actuator was not enabling full boost because the small little port was blocked. Apparently its supposed to be left unblocked. My bad...

good news