Rocker Arm Fell Off And Spring Is Compressed

[chapters707]

Hello all, I am back again WAY too soon after getting my new motor swapped into the 96 GT. It is a stock 4.6 sohc 2v motor. I had been driving it for a few days, it passed smog and was running great. Then at about 150-175 miles on the odometer i noticed a ticking sound going down the freeway. I pulled over and the idle was very rough, car was coming close to stalling and CEL was on. It limped a few miles home and I pulled the codes and got a misfire on cylinders 4 and 8. I checked for spark fuel etc. and all seemed normal.

Today I did a compression test and all cylinders except for #4 were between 180-200 psi which seemed great. Bad part is #4 is completely dead; 0 psi. So I pull the valve cover off and low and behold the second rocker arm from the top (not sure if this is correct term for these cars) had fallen off and was sitting on the bottom of the head. I rotated the crankshaft to inspect the camshaft where it mates with that rocker and it appears smooth and unwarped. No damage is evident in the head from it popping off either. What I did notice is that the spring is still compressed and if I set the rocker arm in place it just slips right off easily.

So my question is how are the rocker arms on these engines held in place, is it purely by the tension of the spring or should there be some kind of clip or other method of securing it in place? Also does the stuck spring give a clear indication of what's wrong? Bent valve maybe or something else? Hoping I won't have to pull this motor again so soon but it's not looking good. Thanks in advance for any thoughts or suggestions.

 

[COramprat]

Cam cage? That is how mine were held in place. Unusual for the spring to be compressed though. Can you remove the retainer?

 

[trinity_gt]

The valve head could be bent, the stem is seized in the guide or perhaps the spring itself is broken. Something (a piece of the piston which may happen under severe detonation) could be wedged between the valve and the seat preventing it from closing.

What did the spark plug look like? Any mechanical damage to the electrodes or insulator?

A borescope through the plug hole might show what's going on in that cylinder. I doubt the engine will have to come out but that head might have to come off...

 

[chapters707]

I'm not really sure what a cam cage is. When you say retainer do you mean what the spring wraps around? I haven't really messed with it yet cause I'm worried about damaging anything further and am not very familiar with this stuff.

Do you think a broken spring could cause it to remain compressed? I am all for exploring the easier fixes before getting elbow deep into a rebuild. Spark plug looked normal just a bit oily. All of the plugs were pretty oily as this engine was quite dirty when I got it and I couldnt clean it thoroughly enough.

One more thing is I didn't have a dipstick tube attached at the time this happened. Could that possibly cause a drop in oil pressure that would affect this? I know it's a Longshot but can't hurt to mention it. I'll look into the boroscope idea. Also I'll attach a photo so you guys can see exactly what I'm looking at. Thanks for the responses so far.

 

[chapters707]

I'm holding the broken one in the first photo. The photo below shows the spring that appears to be stuck compressed.

 

[Sluggie24]

That valve is done. No matter what caused it to hang open, when the piston came up they tried to occupy the same space at the same time. More than likely the valve got stuck in the guide. Head needs to come off.

 

[chapters707]

Okay that's pretty much what I figured. I have decided that I want to pull the motor again and just do a rebuild. It's what I should have done the first time time but I was told the motor had good compression and was in good running condition. That only lasted for 150 miles and this is the only way I can have some piece of mind.

For those of you that have rebuilt 4.6 sohc 2v engines before what kind of price and difficulty am I looking at? My buddy said he had his head rebuilt by a shop as well as machined and compression tested etc. For $350. If it's very difficult or easy to screw up maybe I'll go that route. Let me know what you guys think. I have done a full motor swap, clutch and a bunch of gaskets in my garage so I'm not afraid of some hard work.

I just wanna get this thing in a condition where I won't have to worry about it for a long time. Thanks in advance guys.

 

[chapters707]

Another option I'm beginning to consider is purchasing a reman engine depending how things look once I get the head off. Would be nice to avoid all that teardown and reassembly and get basically a brand new engine with a nice warranty. Have been looking into power train products as well as s&j. Jasper is a bit too pricey for me. Anybody have experience with these brands or another for 4.6 remans? Would love to hear about any first hand experiences.

 

[Sluggie24]

What were the prices of the reman engines? I've dealt with different types of reman engines quite a few times over the years. Most are ok, some have issues. Reman engines from an auto manufacturer are always the highest quality but also the most expensive.

 

[chapters707]

Oh cool I'm glad to hear your experiences with them have been alright. Prices from both companies are around 2.5-3k with shipping and depending whether I return my core or not. That's a little less than a decent sn95 costs around here. I figure it's worth it though cause this way I basically get a brand new one and get a warranty too. And of course I won't have to worry about doing the timing or screwing anything up during reassembly. I just wish I did this the first time rather than gambling with a junkyard motor...