camoracer34

So I recently purchased a 1994 RX7 with an LS6. The oil pressure is reading low, 10-11 lbs at idle and 20 lbs cruising at 2,000 rpm. To me this is way low, should be twice those pressures. Cold start is around 30 lbs.
Problem two. I noticed the cam position sensor is not hooked up. The sensor is there but haven,t located the connector; may not be there as car does not have stock wiring harness. Engine turns over around 4 seconds before cranking and does not idle until warmed to operating temp. The engine seems to be set up for speed density since there is no mass air sensor. Oil temp is good, no knock in bottom end or from lifters. Oil smells good so I think all the bearings are ok. Also, ECU is Electromotive TEC GT if anyone is familiar with this.
Any thoughts or ideas are very welcome.

fruitsalad

iTrader: (5)

First thing I'd check is the OPSU if it clearly has some issues going on with sensors.

camoracer34

The gauge is mechanical. I've already put another one on just to verify the pressure so I know it's not the gauge. Apparently with the Electromotive setup the cam position sensor may not be necessary depending on the tune. Read that somewhere the other day. I'm just not that familiar with the Electromotive setup.
Getting ready to start pulling the engine. Kinda wanted to check the internals anyway. Supposed to be all forged internals.

fruitsalad

iTrader: (5)

Might as well while you can. What's the health of the oil pump like? If it's a relatively old one you might try swapping in a new ported LS6 pump just to see.

camoracer34

Supposedly the engine was professionally built and has around 6,000 miles on it. May be worth trying a new pump before pulling it completely. There was another thread here "epic oil pressure" something or other. That ended up being a cam bearing walking out of place. The symptoms described in that one sound very similar to what I am experiencing.

fruitsalad

iTrader: (5)

It's hard to tell whether it's bearings. Maybe it was built with loose tolerances for some reason? Or maybe the builder ripped or pinched the o-ring installing the pump? Not likely to be that, but that's one of the all-too-common little things.

camoracer34

Just finished pulling the engine and I'm about 100% sure I found the problem. Dropped the pan found one of the main bolts laying in the bottom. When I looked to see which cap it came from I noticed that all the bolts in line with the one that had fallen out were also hanging loose only held in place by the windage tray. I removed the windage tray and checked the others and every single main bolt was loose. The only bolts torqued were the small external side bolts. Going to pull the caps and check the bearings tomorrow. On the plus side, however, I was pleased to find H-beam rods and forged JE pistons. The crank is stock but I've heard they are pretty stout. If the bearings are ok I'll probably replace the stock main bolts with ARP and button everything up.

S10xGN

iTrader: (11)

Were they the stock TTY bolts? Whoever did the motor may have reused the old ones, that could be why they failed. Or someone didn't use a torque wrench. Or just forgot...

camoracer34

They are the stock bolts. Someone must have completely forgot to torque them. The side cap bolts were torqued but none of the mains were. All of the internal main bolts were hanging down from the caps except for the ones with the studs for the windage tray. The nuts for the windage tray were tight and were the only thing keeping those from backing out. It's a miracle the engine didn't suffer a major come apart. I've only pulled one cap so far to inspect the bearing and it actually looks ok with only one spot very slightly worn. If all the other bearings look the same I may reuse them. Definitely going to buy new bolts though.

LS3AEROCPE

I would replace all the bearings before putting the engine back together, much cheaper and less work if there is a problem later?

LS1MCSS

iTrader: (18)

I sure would like to know who the PROFESSIONAL was that built that engine. He sure dicked that one up.

camoracer34

Ok I tore down the whole engine. For the most part everything looked ok. Some rod and main bearings were worn beyond being reusable but the crank and rods themselves were fine. I just finished installing new rod and main bearings and I'm getting ready to button everything back up. Apparently the engine was originally built by a professional shop, I've called them and verified this, but that was several years ago and the car has swapped hands a few times during that period. However so as to not give the shop a bad name I will not mention their name. I've read posts on here about them and they come highly recommended. Hopefully it will be back in the car running with perfect oil pressure before too much longer. While it's out I'm building a custom A/C setup to install and that's going to take me a while longer to do after the engine is back together.