I am having a problem with my 96 LT4 and am hoping for some help. Engine was rebuilt about 2000 miles ago, stock with the LT4 hot cam. No issues until last week. I was driving to work on the interstate going 75 or so and started to loose power and run really rough. I made it to work (about 2 miles) and when I stopped it would not idle. Threw a P0101 code. No misfire code, that has been tuned out.

I had it towed back home and got it cranked again and it seems to be making a noise from the passenger side so I removed the valve cover and found some round plastic parts as well as several tiny springs or at least they looked like springs (see pics below). Also what looks like some water in the valve cover, but none in the oil. I am thinking this could be condensation?

Can anyone help me figure out what is going on? Pics:
Pic1
Pic2
Pic3

 

You got fun
When you crank the engine do you see the rockers go up and down?

At the very least heads need to come off and valve job with new springs, maybe rockers.
If you pull the head and see dings in your pistons - you have bent valves as well.

Sorry to say you may be at the rebuild stage if its really bad.

 

the last pic looks like a style of valve seal that used those coil springs to hold the seal onto the valve guide. my question is where is the rest of this? most likely down in the pan or somewhere else in the engine. if it were me, I would pull the engine apart and start from fresh.

 

Give a photo of all the vavle springs. Looks like Valve stem seal might of somehow came apart. Maybe it didnt drop a valve and just oil fouled the spark plug. Check all the rockers by hand and make sure its all together. Sometimes a camshaft lobe kinda flattens

 

When I saw the last photo I immediately thought of valve stem seals. The problem is -- how did it get out of inside the valve spring? You might have a broken valve spring.

I have seen a broken valve spring that allowed the valve to drop down enough that the piston was hitting it. Everything looked OK at first glance but the noise got us to look at the valve spring, which was broken and the coils were intertwined. There was no damage to the valve or piston. A new valve spring fixed it. Nothing else needed to be replaced.

 

Thanks everyone for the help. I hope to do some more disassembly tonight and will get a few more pictures. As far as I could tell with a quick look this morning, no valve springs are broken.

 

The fact that noise is present = something is bent/broken.

Either the valve guides are to tall, the retainers have an incorrect length (long) or the cam has to much lift for that type of valve seal. The bottom of the retainer has been pounding on the valve seals causing them to fail & causing a bind on all valve system parts. If your lucky bent push rods will be the only damage.

 

 

I took the rocker arms off and took a couple of pictures. From what I can tell, no valve has dropped and the springs look good. I was thinking more about the noise it was making and maybe it was just the miss it had, and the possible cracked manifold I have (planning to replace with headers). I also took a picture of the push rod length, as looking on the web, I found I might should be using 7.200? The engine builder bought them for me, could this cause an issue?

I guess my next step is to remove the head and see what else is going on.

Pics:

Pic4
Pic5

 

You can't just guess at pushrod length. You need to measure to determine what is needed.

Frankly, I'd check around at a couple tool rental places and see if they will rent you a bore-scope to look around the cylinders vs pulling the heads.

 

I never thought of a bore scope. I just ordered a USB one from Amazon for $40. 7mm head should fit in the plug hole just fine. Any excuse to buy a new toy....

 

the wifey bought me one for Christmas. now I need an excuse to use it.

 

That first pic looks like you have water in the oil. I'd drain the oil into a clean pan (clear if you have one) to see if you have water in it. I'd also do a pressure test on the cooling system to double check. Last thing you want to do is ruin the bearings. And if they are already damaged, better to catch it now than after more damage is done.

 

You have coil bind on the springs and it ate the valve seals.
Who ever set up your heads did not know what they were doing and did not check the valve spring hight.

The milkey color is normal for a lt motor they gush water when first put together until the head bolts seal. I use b2 and b1 MR gasket sealer when I put one together.

 

Would fixing this require removing the heads for a rework, or is this something that can be fixed with the heads on the car? Thanks Jay

 

Built plenty of LTx engines. Never had one "gush" water and never used gasket sealer.

 

Assuming no cylinder or valve damage, this can be repaired on the car. Having said that, you need to find out what springs they used. Stock LT4 springs work fine with the LT4 HOT Cam on a daily driver. Either you have a different cam than you think or different (possibly LT1) springs.

The only issue with LT4 springs is that when really pushed (HPDEs, track days, time trials, racing w2w, or Extensive 1/4 mile use) and they lose spring pressure fairly quickly. They do not bind with the HOT Cam and 1.6 rocker arms.

You should probably dig through your receipts and find out EXACTLY what cam and springs were installed for your rebuild. From there you can determine which valve springs to buy, as well as corresponding retainers and locks. Obviously you will also need new valve seals.

You can check the pushrods by rolling them on a flat surface. Any that are bent will be obvious. Lots of threads regarding how to determine correct pushrod length. However, unless your heads and block have been decked a significant amount, stock length will be fine.

There are also many threads regarding on-car valve spring swaps. I prefer to rotate one cylinder at a time to TDC. When you remove the valve springs, the valves will drop ~1/4 inch and rest on the piston top. Poke a soda straw through the spark plug hole to ensure the piston is in fact at/near TDC for the cylinder you are working on. Sometimes, on easy to reach cylinders, I use compressed air via a fitting threaded into the spark plug hole. The compressed air keeps the valve in place and you don't have to worry about rotating the cylinder. Other guys cram rope in the cylinders. It works, but personally I find that to take far too long and you risk getting dirt/debris in the cylinder.

 

The heads were built with the GM HotCam kit:

http://www.jegs.com/i/Chevrolet+Perf...80002/10002/-1

This had everything in one kit with the exception of the pushrods that the builder bought for me.

Thanks for all the help, I will update the thread after looking in the cylinders this weekend.

 

First, there has been a significant deviation in your valve train from stock. LT4's came with a NON adjustable pedistal type valve train; the rockers simply were tighten down onto the top of the pedestal (which is a rocker arm stud with a shoulder built into it) and the retaining nut (which appears the same but is NOT to be confused with the adjusting nut on a normal valve train) is tightened to a set torque value.

Your LT4 "Hot Cam kit " substitues an adjustable rocker arm stud and nut.

I'm NOT saying this is what happened, but if your builder attempted to adjust the valve train according to STOCK LT4 spec's and procedures, every thing on that valve train is / was completely out of whack.

LT4 hot cam with 1.6 rockers lift = 0.525 inch; max lift for LT4 hot cam springs before coil bind = 0.525 inch; so yes adjustment and geometry is pretty crucial.

The good news is that new LT4 Hot Cam springs are about $45 , which with a set of valve seals should get you up and running, after of course sorting out any valve train geometry problems that may, or may not, require a new set of push rods of the proper length.

 

Quick question. I have the rocker arms off at this point. Is a compression test valid? I am getting only 30 PSI on one of the cylinders. Not sure if it is my gauge or not, but am getting 120 on one of the other cylinders. What in the heads could cause this?

I used my borescope and see no damage to the cylinder walls or the pistons. Pistons have a good bit of black soot on them though.