jimnina

I apologize for the LONG SAGA, but thought everyone needed a sad story Hopefully some one will show some mercy after reading.
It all started with an engine miss. I traded a Class 'A' RV for a 94 corvette. Going into this I knew the vette had an engine miss. I checked plugs, wires, injectors, etc and all appeared to be good. Seeing from the different threads I looked at the OptiSpark as a possible culprit. The last day I drove the vette it was harder to start and ean badly, so I was assuming that the OptiSpark was getting closer to its final death. I ordered an Optispark on line and installed it with little issue. Once I had the vette back together and tried to start it, I found it would crank but no joy on starting. Checked Spark which it had plenty of. So I turne the key on and listened for the fuel system to charge up, which it did. So I was scratching my head saying why won't the vette start. So I went under the hood and pressed on the relief valve on the injector rail and fluid came out under pressure just as I thought it should, The problem is that it wasn't gas, it was water. After reading threads on the forum I found that the 'Water Basin' better known as the fuel filler accessory had the drain plugged and the water from the current rain had went into the fuel tank. Once I broke off 70% of the bolts due to rust I was able to remove the filler tube and pump so I could siphon out the 4+ gallons of water that had accumulated in the tank. No I have cleaned the tank and primed the injector ril with fuel it was time to start the vette. As the vette started I noticed a noise that had not been there when I parked the vette, To my dismay it sounds like very rod in the bottom end spun?? The question is would the water cause a hydro lock that could affect the bearings? Is the oil pump pumping oil ( the oil pressure gauge says 30-40#'s). I'm at a loss of what to look for.
Thanks

crowz

I know the water will ruin the injectors and can cause them to stick open thus pouring gas or in your case water into the engine. Start with an oil change and hope for the best.

383vett

From what I'm reading, you had water in the tank, not the crankcase. Water in the fuel tank will not cause hydrolock.

jimnina

Hey Crowz and 383Vette,
Thanks for the replies.
I was thinking of the hydrolock due to water in the cylinders via the injectors. I wouldn't think that much water could get into the cylinders, but I'm grabbing at straws. I am going to try the oil change this weekend and see what happens.

ghoastrider1

jimnina

Upon further review I have noticed that even though the oil pressure gauge is reading 30-40 psi I don't see a lot of oil in the head? Is this normal for a vette to show such small amount of oil I used to taking the oil filler cap off and seeing oil soaking the rockers and such. Is it possible for the gauge to read pressure and it really doesn't have much. The oil gauge does fluctuates so I'm assuming it's working.

383vett

There is a baffle under the filler cap. You shouldn't be able to see the rockers. If the head wasn't getting adequate oil, the lifters would let you know.

Hot Rod Roy

What do the spark plugs look like? If you don't know how to read them, can you post a picture of them?

jimnina

The plugs were replaced about 1500 miles ago by the people I bought the vette from. I haven't pulled them since about a week after I got it. There is no baffle under the filler cap?? I can see the rockers and they do seem to have more oil after I changed the oil and filter. The change didn't help the rod knock much at all and there wasn't much discoloration of the oil, so I guess I will be pulling the pan and changing out the bearings. I had other LT1's, and other motors, and have never had one spin a bearing no matter how hard a ran it. Pretty frustrating to say the least.

Hot Rod Roy

This is not a stupid question. If you've had any water in your combustion chambers, the spark plugs will tell you the story! It doesn't matter that they were new 1500 miles ago. What do they look like NOW?

jimnina

Hey Hot Rod Roy,
Thanks for the reply on the plugs. Good point since the problem wasn't there 1500 miles ago. I will pull the plugs over the weekend, weather permitting, and give an update afterwards.

s carter

I have a few questions/comments, does the Engine still have the miss, is it running a little Rough. is it a manual trans.

I ask because if the Engine is running rough with a Worn Dual Mass Flywheel or a lite racing Flywheel it might Magnify a horrible noise. that newer Corvette owners may not be comfortable with.

Have you done a compression test?
Is the noise high up in the motor (in the Heads) loose carbon. you may inadvertently top cleaned your Engine. pull the plugs out do the compression test, and while the plugs are out spin the with no plugs and blow out any bits of carbon that might be hiding with in.

jimnina

Hey S Carter,
The new optispark seems to have fixed the miss I had. It is an automatic and the knock was not there before I installed the optispark. The engine did start running much worse before I replaced the distributor, hard to start, barely idling, running badly. I now suspect that the water was getting into the gas tank before I finally parked the car and that is why the other symptoms cropped up. It did seem that cylinder #7 wasn't firing correctly and that was where I think the miss was coming from. That was the only cylinder that when I unplugged the injector from #7 the engine didn't run worse. I have not done a compression test, but since I'm going to have the plugs out I should go ahead and perform a compression test. Your comment on the carbon does make sense but I have never heard a carbon knock as bad as the vette has, but I really don't see how I could have a rod knock, since it wasn't there before. I like the carbon option much better. Once I pull the plugs, run a compression test, and check for carbon particles I will post an update. It's suppose to be nice here in central florida this weekend so I will try to do the tests this weekend. There is a big Bike Event in Sarasota that might have a higher priority though

s carter

Since you feel #7 is a problem Cylinder pay extra attention to it as Hot Rod has inferred spark plugs can tell a story. take a good look at the Electro if you have the carbon in the Cylinder odds are it would be crushed. Confirm the gaps as you go.

jimnina

Update of the day.
Well, I pulled the plugs and the look fairly good, other than some carbon. I also performed a compression check on all of the cylinders except #8, still trying to figure out how to get the compression gauge on that one. Compression was #210 on all but two cylinders. #3 was low at #180 and #7 was not as low at #195. Plug #7 gap is much smaller, maybe due to carbon? In an earlier post I mentioned #7 showed no difference in how the engine ran when I unplugged the injector. It was actually cylinder #5.

I did not see much of anything coming out of the cylinders when I cranked it over so I'm not sure about the carbon knock. I'm going to see about getting a cylinder camera to see if I can take a look see.

s carter

They seem a bit nasty for 1500+- mile plugs, but in that time you have changed an OptiSpark and removed a lot of water. so either install a set of new plugs or give that set a good and proper cleaning they seem a bit Oily, and continue with your plans looking for a source of knock.

Also confirm the plugs are correct for the car.

Hot Rod Roy

Carter is being nice!! Those plugs are a mess! For one, if you knew how to read plugs, you would have numbered them for us. For number two, we need to see the insulators in the tip of the plugs. The photo's need to at an approximate 45* angle to see the insulators accurately. For number three, you have aluminum heads on your engine, which I'm quite sure use gaskets on the spark plugs. These are taper seat plugs for iron heads, which don't use gaskets. No wonder they look so bad!

If I'm right on the plugs, the correct plugs for your engine will have longer thread lengths, so as a result of using these shorter thread length plugs, you'll have some carbon buildup in the threads in your heads. Install your new plugs, but don't tighten them. Remove them and wipe the carbon off the threads of the plugs. You might repeat this process to remove as much carbon as practical before you tighten your plugs.

Somebody please correct me if I'm wrong about the right plugs for this '94 engine. (My '84 has iron heads, and uses taper seat plugs.)

You don't need a "cylinder camera" to look inside your engine. You won't learn anything.

desertmike1

These are my old plugs from my 95, you'll notice the taper seat, and plug length at 11 threads.. these are stock A/C Delco's

Note; #6 cylinder had water ingression, and the plug is literally being "Steam Cleaned"

https://www.corvetteforum.com/forums...1&d=1421032560

aDigitalPhantom

I am not very good at reading spark plugs, but it looks to me like it is or has been running rich.

Cliff Harris

with Roy.

I thought all the aluminum headed engines used spark plugs with gaskets. Maybe the LT1s are different. I know that is true of L98 heads (at least the stock ones...).