Help! 1994 LT1 Service engine soon light turns on and off

[John Robinson]

Well I removed my shroud and I had dirt packed into the top part of the radiator and ac condenser. I first used compressed air and then I lightly brushed the fronts of the radiator and condenser. Then I rolled the car into the drive and used the hose to spray water in both directions on the radiator and condensor. At first it was preatty brown but it cleared up so i am waiting for it to cool off tonight and then I will put it back togeather. As thin as those units are no wonder a little bit of debree will cause over heating. It will be interesting to see how much if any cooler it runs.


I will say right now I will be only putting two screws back in the sides of the shroud. All I can say is am sure glad my minister was not here when I took them out.

 

[John Robinson]

Thought I would report in on how my car is doing with heating up. Since I cleaned the radiators I now only see 194 to 197 driving in town and on the road. In stop and go traffic I have gotten up to 206. Waiting on trains it gets to 198 ro 200 and then goes back down to 196 while idling. That is about 20 to 30 degrees cooleer than it would do before cleaning the radiator.

One thing I have noticed is that the temp stays around 194 until the oil temp gets above 200 and then it goes to 197.

Oh I forgot one time it went to 210 and when I checked the oil temp it was at 244

 

[SnakeDr]

Meant to follow up on this a while ago. I had a mechanic take a look at the my car for a possible rear main oil leak around early May 2013. Turns out the intake manifold is leaking. While he was checking for the leak, he mentioned my water pump is weeping. This is probably the cause of my concerns, the water pump is partially on its way out. I have already purchased a OptiSpark (came in about a week ago) and have a brand new water pump in my possession already

Ironically we are in the middle of a heat wave in NJ. Last year I drove the car during the heat wave and had some concerns however the A/C wasn't working. By the time, I fixed the A/C, flushed and cleaned the system summer was over. Well, today I drove around with the A/C on and it appears to be somewhat okay. On the highway, with the A/c on, I was in the upper 190's. In traffic, it crept up to about 220. I'm sure it would have crept a little higher in stand still traffic.

So I'm hoping to replace the opti and water pump in the next two weeks. We will see then if my cooling system improves even more. I'm thinking it should improve significantly.

 

[SnakeDr]

Got her up on jack stands. I managed to remove the water pump yesterday. Bearings and seal was bad and I'm surprised it wasn't a heavier coolant leak. I'm sure it was weeping. Tonight, I will try removing the Harmonic balance pulley and opti spark.

 

[SnakeDr]

Got her almost back together. I had to purchase a Kent Moore J-39046 hub removal. Just sold it to get my money back. Replaced all three timing cover seals, installed petris opti spark, new crank hub and water pump. Bought another set of a/delco wires. Repaired dreaded intake manifold leak. Had the intake itself powder coated.

Sent out power steering pump and had it rebuilt for $50.00 through rockauto.com. Waiting for a couple of other small parts to be delivered before firing her up. Should be close Monday. Been working on her in the garage little by little after work. Did some cleaning and painting also. Almost got her back together.

Finishing touch...my used cat back borla exhaust. Installing this weekend.

 

[Wegone]

Not sure if anyone posted this, you do realize that factory settings on the fans with ac off are fan 1 on at 225, fan 2 on at 2 235, plus or minus 5 degrees.

 

[SnakeDr]

Not sure if anyone posted this, you do realize that factory settings on the fans with ac off are fan 1 on at 225, fan 2 on at 2 235, plus or minus 5 degrees.

Thanks for the information. I don't believe so but makes sense. The image of a needed approaching 235 is distressing but in reality its normal operation. Engine should be quieter due to the bad water wp bearing. As time went on I got used to watching the needle and hearing the fans kick on and off. Anxious to see how she runs.

Are those all your kids (Corvettes) in the photo? All of them wearing their Sunday's best!!

 

[Wegone]

Thanks for the information. I don't believe so but makes sense. The image of a needed approaching 235 is distressing but in reality its normal operation. Engine should be quieter due to the bad water wp bearing. As time went on I got used to watching the needle and hearing the fans kick on and off. Anxious to see how she runs.

Are those all your kids (Corvettes) in the photo? All of them wearing their Sunday's best!!

Thanks, yes 4 of them I also have 96 CE LT4, one day I'll get them all out for a new family photo. 36 years of Corvette ownership. You can always get a manual fan switch kit so you can control when you want to turn them on or have it reprogrammed to a lower temp. I have my ZR-1 fans set to come on at 205 both fans.

 

[SnakeDr]

Got the engine back together. Need to add oil and coolant before cranking her over. Have some small odds and ends before a test drive including replacing 20 year old brake lines.

 

[SnakeDr]

Post and "POOFF!!!!!"

Got her back together. Fired her up last Friday night. She started right up. Only issue is my power steering is not working with the new pump. Must have air in the system even after bleeding.

Other than that. Engine sounds great. Idles good. Borla exhaust sounds great. Temp gauges look good and really not paying them any mind. Weather has changed and its not as hot. With a solid pump its not gyrating I believe like it was before.

 

[SnakeDr]

Got her back together. Fired her up last Friday night. She started right up. Only issue is my power steering is not working with the new pump. Must have air in the system even after bleeding.

Other than that. Engine sounds great. Idles good. Borla exhaust sounds great. Temp gauges look good and really not paying them any mind. Weather has changed and its not as hot. With a solid pump its not gyrating I believe like it was before.

It's been a while since I've posted on this site. Well its time to renew my inspection sticker. I finally resolved my power steering issue (four used pumps later). Now my service engine soon light is back on. I had pulled my codes and it pointed to a MAP sensor. However, I wonder its my knock sensor wires grounding out on the heat shield. I found some replacement LT1 knock sensor wiring on ebay. My original solution I noticed was sticking to the heat shields.

My biggest challenge is not actually fixing the problem itself but getting the car up high enough to work on it.

Other than that...It's a blast to drive and the exhaust sounds angry.