LX 5.0

Hey I just bought my second LX 5.0 this time a 1990. I had a 1989 12 years ago. This car is very modded and I am having a over heating problem. I think my set up might be to much for a OEM radiator which it has. Here is a list of my mods.

Vortech V-1 supercharger 8 psi
Anderson style powerpipe
42lbs injectors
Lightning MAF
GT40 heads, with upgraded springs and 3 way valve job.
Scorpion 1.6 full roller rockers
Manley hardened pushrods
GT40 upper and lower intake
JCP custom cam
Accufab 70mm throttlebody and spacer
New Melling oil pump with new ARP pump drive
Aermotive stealth 340LPH fuel pump
Kirban adjustable fuel regulator
BBK crome unequal headers
BBK O/R H pipe
Magnaflow mufflers
Gripp rear upper and lower control arms
Welded subframe connectors
Welded Panhard bar
Aluminum driveshaft
355 gears
275's and 255's Nitto
Lowered and aftermarket shocks
T5
OEM clutch

The previous owner said the supercharger has only been on the car for about 200 miles. After about 20 minutes the car over heats. I replaced the radiator cap. I only saw some water that had leaked around the edge of the hood and battery area. Each time it over heats I need to put about half a gallon into the radiator. After a 10 minute ride today I put it on ramps and saw no leaks under the car around the water pump and hoses. Also the car didn't leak out any fluid and the overflow tank was at normal level. When the car does over heat the overflow tank is about 3 inches from the top and somewhere under load coolant leaks out. The OEM radiator I have is in good condition. Can a OEM radiator handle my set up? I just got it on the road this week...
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• Back after 3 years

GT Nate

has the thermostat type cooling fan doesn't it? Could be it might need to be changed, it might not be keeping up with the engine speed.
Other's have installed electric fans which come on when a temp probe gets hot enough.

TrimDrip

mine did that with a cheap aluminum 3 row and taurus fan. I upgraded to a 2.5" 2 row factory replacement radiator from jegs and didn't have a problem anymore.

does the car overheat traveling down the highway as well? or only when you stop.

wbrockstar

Are you 100% positive its leaking externally?? I think you'd notice if a half gallon of coolant were coming out of the overflow bottle while driving?? It would probably be all over the driver side engine bay from the wind blowing it while driving??

You'll normally see evidence of it (steamy white smoke from the tailpipe) if its bad,but if it has just started it might not be very noticeable yet?? Im referring to an internal coolant leak (i.e.-blown head gasket) It can happen very quickly/easily on a Foxbody with
a supercharger with just one or two trips with detonation.Detonation= a pinging/knocking noise similar to the sound you hear when using cheap low octane fuel & driving up a steep hill under heavy load.If it was already overheating when you bought the car,the previous owner could have caused it himself and instead of dealing with it,just got rid of it?? A blown head gasket will usually cause
the engine to overheat rather quickly vs a small coolant leak or undercooling condition. The easiest way to verify/rule out a head gasket leak is by pulling the plugs to see if any are wet with coolant and if one or two plugs are wet,do a compression test on those cylinders & the cylinders next to them
(A head gasket normally blows between two adjacent cylinders) Compression will be lower than the other cylinders,if its blown. Detonation is the #1 thing to look out for when running a supercharger on a Foxbody, so if you hear it lift quickly.If the gasket is not leaking internally,check the thermostat to make sure its not sticking closed.That will
also cause the engine to overheat quickly.
To check it: let the engine run til it reaches operating temp,squeeze the upper radiator hose to make sure its hot & soft.If the hose remains stiff (hard to squeeze) that indicates the tstat is stuck closed.
To make sure the water pump is working,feel for a surge of coolant flow when you release the radiator hose after squeezing it.You'll also see coolant flowing freely out of the ends of the radiator tubes,with the cap removed for viewing.

LX 5.0

The cooling problem appeared to be air in the system. However when I drained the tap water to replace with coolant only a gallon came out. Shortly after the car wasn't over heating it significantly started running horrible. It barely ideals and shows signs to my knowledge of air fuel issues. It's barely derivable. It went from being sensitive when cold but running good otherwise to absolute crap. My oil looks clean on my dipstick. I cleaned my mass air sensor. At this point I am 2 weeks out from getting a reputable shop that knows these cars well to look at it. Do you guys recommend a place to take it to in North East Florida? Thanks for all the replies. I have not done a compression test yet. Unfortunately this time of year I have hardly any time off.

TrimDrip

i would be willing to bet money that your thermostat doesn't have a hole drilled in it to let the air escape. air won't open it. if the fluid level ever gets low in the engine, your temp gauge will skyrocket all of the sudden.

don't know of any shops. sucks that it is giving you trouble.

also, your set-up is very similar to the one i have. if you get time to troubleshoot it some, i could help you with it. I have put 80k on mine and about 70 of that was boosted from a vortech. i bought the car stock and did everything myself, including tuning it with a moates qh.

Urambo Tauro

I can't stress enough how important it is that the system gets burped of air. These 5.0s are particularly sensitive to this on account of not having a high-point bleed valve (something I envy the V6s for having). Anytime there is a loss of coolant, whether it leaks or boils out, has the potential to leave a pocket of air up by the thermostat to keep it from opening.

At any rate, it sounds like you did in fact find an air pocket and finally have the system filled properly. So does that mean that the overheating issue is resolved now? Are you moving on to the "runs rough" issue? Your recent post is unclear as to whether you've resolved to take it to a shop somewhere, or are planning to do a compression test next.

LX 5.0

Took awhile to get the car to a shop. Pulling plug wires off the distributor, spark test, and compression are basic tests I could of done but I figured the mechanic is going to go through all the steps himself. Head gasket was blown between cylinder 7 and 8. The Block was damaged where the head gasket blew. Also over heated damage shows from the freeze plugs being deformed. If the block if savable It will need to be shaved as well as the heads. I literally barely drove the car since the purchase and now I need make some big decisions. I'm looking into buying a short block. based on my build shown on my first post what should my compression be? All the cylinders other than 7 and 8 which were flat only had 75 compression!

TrimDrip

based on what you posted, you would be right around stock compression of 9:0:1.


you had other problems than compression. What type of tuning device do you have?

LX 5.0

I'm going to ask the mechanic about the computer today. The place i brought it to specialty is Chevy but they are local and fair. The place I wanted to take the car was a hour away were booked up for 2 weeks and were not responsive regarding setting up a appointment. I'm going to decide weather it's worth paying for the engine to go to a machine shop or just starting over with a short block... The car is really clean and I want to get the motor right the first time. Also I'm thinking about not installing the supercharger.