I took my '94 LT1 down to NJMP Lightning last Saturday for my very first ever HPDE, and that might just have been the most fun I've ever had in my life (right until the end). I recently got a pair of 9.5" sawblades for the front to go to 275/40/17 Falken Azenis 615k+ tires all around (thanks to FAUEE and MatthewMiller for the advice on tires and brakes!). The stock JL9 brakes held up fine through the day, and I had no trouble keeping up with the pace car run by the organizers (and I was in fact held up a few times by much newer, fancier cars). I was amazed at how much cameras erase the elevation gain going into T1.



Unfortunately, on the last turn of the last lap of the last session, the car erupted in this thick white smoke. I pulled over immediately to see that the thing was gushing coolant and spraying oil around the engine bay. The organizers were telling me I was actually spewing oil out of the back of the car too (they said 15 bags of oil dry were used to clean that all up). This is where some of my confusion begins.



In my shock and disappointment at my beloved C4 having its first real breakdown in my care, I was absolutely terrified something really serious went wrong, like somehow a head gasket. I was confused initially as the car showed no indications of anything going wrong other than the white smoke. It was happily pulling north of 90 MPH in 5th gear before the white cloud showed up, and the half second it idled when I came to a stop did not sound any different. Regardless, oil in the tailpipe sounded like a huge issue, especially with the oil coming out at the same time as the radiator hose bursting. I have to move in a month, and I'm not the most skilled mechanic, so I was afraid this disaster might spell the end of my time with it. The hose connecting the water pump to the tee blew out, shown below:



However, I got the car back this morning after having it towed up from Millville, and I took a closer look at where the oil was coming from, and I discovered that this connector between the breather pipe and the throttle body had split around the bottom, which was why I did not see this immediately:



Does anyone have any advice on how best to proceed here? I don't think anything very serious happened, but I want to know for sure that I'm addressing root causes and not just symptoms. My initial thoughts are that I should replace this hose on the PCV breather and all the radiator hoses, then see if it will start and run, and go from there. I have some fear that the optispark got soaked from the coolant hose blowing out, but that seems like something I'll best be able to assess if I can start the car again. The coolant coming out was orange rather than the green of ethylene glycol antifreeze, so does that mean I should refill with dexcool? Any advice on getting this thing fixed up and back out on the road would greatly be appreciated.

 

yeah the track is where weaknesses show up that you may not have thought of, has happened to me a couple times.

Were your temperatures running fine beforehand?

I'd do just as you said, replace hoses, refill with dexcool, repair the line, change the oil out and make sure theres no coolant in it

 

Looking back at footage, the temp gauges never got anywhere extreme. I had the oil temp readout on gauge cluster, and the highest I saw was 248F. I know that's on the hot side, but I don't think that's catastrophically hot (please correct me if I am wrong).

I checked the dipstick right after the incident and again today two days after, and the oil there is full and remarkably clean. I'll get that oil changed ASAP so I can look more closely at the oil that's in there.

 

You are lucky worse didnt happen.

in 2005 the radiator hose blew out on my 93 while racing at nelson ledges as i went into a turn

i spun out (but stayed on the track) as the slippery antifreeze got all over my tire contact patch.
.

 

Based on your description and pictures it would appear you dodge a bullet by being very careful in the aftermath.
I think you are on the right track as far as your next steps in bringing her back to life.
When you have it all back together and try to start it will tell you a lot about what it needs next, if anything.
Good luck and keep us informed as you go.

 

I still don't understand where the oil came from. I understand the coolant but not the oil. Dan

 

Are you sure it lost oil? The split breather hose pictured shouldn't have oil in it. Crankcase vapors, yes. Oil, no. If the oil level in the sump still shows nominal on the dipstick, it didn't loose oil. A sudden coolant deluge hitting a hot exhaust makes quite a smoke-show.

Depending on where you live and the likelihood of the car encountering freezing conditions, consider using pure water with an anti-corrosion additive for coolant for HPDE days. If something happens again, the track crew will appreciate the foresite.

When you change all the hoses also change the thermostat. The LT1 thermostat has a little spring-loaded disc on it that closes off the bypass circuit to allow full-flow circulation through the radiator. BUT. At high-ish RPM the water pump is capable of producing cooling system pressures that can be harmful to the plastic tank radiator. (And hoses?) At high RPM the disc is pushed off its seat, bypassing some of the flow and reducing the pressure at the radiator. The hose that blew is subject to the highest pressure. The thermostat bypass valve may be sticky or acting up. Replace the thermostat.

For the opti all you can do is get it running and begin driving it again. If it runs for a few drive cycles with no problems, you probably won't have trouble. When I suffered a coolant explosion similar to yours, it was on my hoist while working on the car. I grabbed the water hose and douched the coolant off of my nice clean NCRS-prepped engine bay. I didn't even think of the opti. But it got douched and died a few drive cycles later. Your 94 has the opti vent system. If any condensation formed internally the vent system should extract it over time, but you have to get it running for the vent system to operate.

Sounds like you had fun. My parting thought is "How old are the flexible brake hoses on your car?" If they are the originals, I'd think about replacing those too before the next track day. Cheers.

 

the PCV system is my guess, though im not sure why so much oil came out


also (to IHBD comment, i dont think 1994 optispark had a vented gen 2 setup until 95-96

 

My wild *** guess is if your PCV system can shoot out so much oil it can be seen driving down the track you might need new rings. Dan

 

If it is full of oil, it is probably just Dexcool on the track that they think is oil. I think you should start the car and see how it sounds/runs after you repair the busted hose,

 

Having never owned an Lt1, but having owned an LT5, i had no idea this concept was shared.

For any LT1 owners that track their cars, can you run the Lt1 on track at redline or just below for almost a full 20min session? On my LT5 i cannot do that. The result is exactly what you experienced.

On the LT5 i had to remove the tstat and jimmy rig the bypass valve to force the coolant through the (upgraded aluminum) radiator with upgraded silicone hoses.

Does this need to be done on the LT1?

 

Got the hoses, thermostat and fresh serpentine belt (recommended by my dad since the old one got soaked in coolant) in the mail today. Thanks for the advice all, hopefully it's good news later this afternoon! As a side note, @IHBD , one of my projects to prepare the car for the track was a set of stainless steel braided brake hoses, so no worries on that front

 

If you haven't changed the oil yet, do a Google search on Blackstone Laboratories. They will send you a container you can put a sample of your discarded oil in and an envelope to mail the container back to them. They will then send you an analysis of the oil comparing it to other samples they have seen from the same engine model. I do this every time on my LS7 looking for metal bits that shouldn't be there (please don't get THAT conversation started here!). The analysis is very detailed and they will include conclusions like "you've got coolant in your oil"... or hopefully you'll get the "your oil is normal" conclusion. Either way, more information is better and will give you some peace of mind. Good luck.

 

Well, I finally got fresh hoses on and got ready to fire it up. Unfortunately, it will not start. Cranks just fine. I didn't have anyone around to help me check for spark, but my money is the opti is gone. Unfortunate. Long weekend ahead of me I guess...

 

The opti is really not that bad of a job. The hardest part is remembering where each plug wire goes. Pull the intake tube, pull the serpentine belt, pull the water pump, pull the 3 bolts for the crank pulley, you're at the opti.

 

If your opti is original, you could rebuild it with a cap and rotor. Dan

 

As Dan said, at least keep it if original. It will have the Mitsubishi sensor which are the best and not produced any more.

 

Every time I see a thread where the opti comes into play, I always ask myself why. Why did they do that? Why? I'm so glad I don't have one. I've read countless threads and posts about the nightmares regarding that thing on here.