TurboMinivan
Still plays with cars
- Location
- Lehi, UT
I spent a couple hours helping my friend Mike wrenching on his CJ5 last night. The newly-rebuilt engine starts and runs, but only makes 7-10 psi of oil pressure. We cannot figure out why. Let me give you all lots of background info to see if there is something we are missing.
Mike bought this '82 CJ5 in the spring. It had a 4.2L straight six that would cough and sputter, but it didn't run properly at all. Mike decided to ditch that engine and go with something he knew better: a small block Chevy. In an amazing coincidence, at that same time a co-worker was literally throwing away a Chevy 350 long block engine--this had been in his boat, but he didn't winterize it and the block cracked. Everything else on the engine seemed okay, so Mike found a bare 350 block (with the same casting number as the ruined block) and bought it.
This replacement block looked pretty good and the bores measured well, so he did a Roadkill rebuild: he dingle ball honed the cylinders, then swapped over the crank/rods/pistons from the cracked block engine. He used new rings, bearings, and seals throughout, and covered all the critical parts with assembly lube. He also swapped over the oil pump, the roller camshaft and lifters, the pushrods, and the heads (L05 TBI style). Mix in a carb and an aluminum intake, a new distributor, and into the Jeep it went. Everything seemed perfect... until the disasters began.
Disaster #1: somehow Mike managed to fill the engine with water. I know the engine got rained on briefly with the open intake manifold on it. Worse, Mike says while he was filling the radiator, he had water coming out the breather hole of one valve cover. Tracking down that bizarre event, Mike saw that he had accidentally forgotten one head bolt on that side. He swears he didn't fire the engine while the water was in it (which would not have mattered anyway for reasons I will explain below). He completely drained the engine, added new oil and filter, let it run briefly, then drained it and replaced it with another pan full of fresh oil.
Diaster #2: Mike noticed the engine made NO oil pressure at all. Soon it dawned on him: there was no oil pump drive shaft in the engine. (Oops.) He drained the oil again, dropped the pan, installed a drive shaft, then put it back together and poured in another batch of new oil. Now when the engine fired up, his mechanical oil pressure guage needle finally moved... all the way up to an indicated 10 psi max, and that only when he would rev the engine.
Disaster #3: while revving the engine a few times, suddenly there was an 'explosion' of engine oil under the Jeep. Mike shut it down and began investigating. During the last oil filter swap, the gasket came off the removed filter and stuck to the block. (I've always heard of this, but I've never seen it happen in life until now.) Mike installed another new filter, this time making sure the old gasket was not hiding in the oily mess.
Back to the main problem. We started asking ourselves what might cause low oil pressure. Could the old oil pump be bad? Did it get ruined by the water incident? A new Melling pump was pretty cheap, so he bought one (their high volume model) and we installed it last night, then added yet another pan full of fresh new oil. We unplugged the distributor so we could let the engine crank without firing, and once the pump primed we were rewarded with an indicated 7 psi of oil pressure. Wondering if somehow the pump wasn't fully primed, we yanked the distributor and used Mike's drill with one of those oil pump priming tools. No matter how long we spun the pump, it never made more than 7 psi. Wondering if the gauge was bad, we tried another. No change. We started working backwards. Eventually we got to the engine's oil pressure port (at the top of the back of the block). We left that port wide open, then cranked the engine to see if we'd get a gyser. All we got was a small dribble of oil. Mike reinstalled everything to operate the gauge just to prevent this mess.
What on earth is going on here? It's weird. With the engine running, it's quiet. If the engine got destroyed in some way, surely we'd hear some sort of knocking noise... wouldn't we? With the engine running, Mike removed the passenger valve cover. The valves were happily bouncing up and down, but there was barely any oil present (and certainly nothing was flinging off and making a mess like it should). Clearly, something isn't right... but because it is so quiet, were there no oil pressure guage he would have jumped in and driven off. Obviously, he doesn't want to do this and ruin the engine (assuming it is still okay).
Any ideas? We're stumped.
Mike bought this '82 CJ5 in the spring. It had a 4.2L straight six that would cough and sputter, but it didn't run properly at all. Mike decided to ditch that engine and go with something he knew better: a small block Chevy. In an amazing coincidence, at that same time a co-worker was literally throwing away a Chevy 350 long block engine--this had been in his boat, but he didn't winterize it and the block cracked. Everything else on the engine seemed okay, so Mike found a bare 350 block (with the same casting number as the ruined block) and bought it.
This replacement block looked pretty good and the bores measured well, so he did a Roadkill rebuild: he dingle ball honed the cylinders, then swapped over the crank/rods/pistons from the cracked block engine. He used new rings, bearings, and seals throughout, and covered all the critical parts with assembly lube. He also swapped over the oil pump, the roller camshaft and lifters, the pushrods, and the heads (L05 TBI style). Mix in a carb and an aluminum intake, a new distributor, and into the Jeep it went. Everything seemed perfect... until the disasters began.
Disaster #1: somehow Mike managed to fill the engine with water. I know the engine got rained on briefly with the open intake manifold on it. Worse, Mike says while he was filling the radiator, he had water coming out the breather hole of one valve cover. Tracking down that bizarre event, Mike saw that he had accidentally forgotten one head bolt on that side. He swears he didn't fire the engine while the water was in it (which would not have mattered anyway for reasons I will explain below). He completely drained the engine, added new oil and filter, let it run briefly, then drained it and replaced it with another pan full of fresh oil.
Diaster #2: Mike noticed the engine made NO oil pressure at all. Soon it dawned on him: there was no oil pump drive shaft in the engine. (Oops.) He drained the oil again, dropped the pan, installed a drive shaft, then put it back together and poured in another batch of new oil. Now when the engine fired up, his mechanical oil pressure guage needle finally moved... all the way up to an indicated 10 psi max, and that only when he would rev the engine.
Disaster #3: while revving the engine a few times, suddenly there was an 'explosion' of engine oil under the Jeep. Mike shut it down and began investigating. During the last oil filter swap, the gasket came off the removed filter and stuck to the block. (I've always heard of this, but I've never seen it happen in life until now.) Mike installed another new filter, this time making sure the old gasket was not hiding in the oily mess.
Back to the main problem. We started asking ourselves what might cause low oil pressure. Could the old oil pump be bad? Did it get ruined by the water incident? A new Melling pump was pretty cheap, so he bought one (their high volume model) and we installed it last night, then added yet another pan full of fresh new oil. We unplugged the distributor so we could let the engine crank without firing, and once the pump primed we were rewarded with an indicated 7 psi of oil pressure. Wondering if somehow the pump wasn't fully primed, we yanked the distributor and used Mike's drill with one of those oil pump priming tools. No matter how long we spun the pump, it never made more than 7 psi. Wondering if the gauge was bad, we tried another. No change. We started working backwards. Eventually we got to the engine's oil pressure port (at the top of the back of the block). We left that port wide open, then cranked the engine to see if we'd get a gyser. All we got was a small dribble of oil. Mike reinstalled everything to operate the gauge just to prevent this mess.
What on earth is going on here? It's weird. With the engine running, it's quiet. If the engine got destroyed in some way, surely we'd hear some sort of knocking noise... wouldn't we? With the engine running, Mike removed the passenger valve cover. The valves were happily bouncing up and down, but there was barely any oil present (and certainly nothing was flinging off and making a mess like it should). Clearly, something isn't right... but because it is so quiet, were there no oil pressure guage he would have jumped in and driven off. Obviously, he doesn't want to do this and ruin the engine (assuming it is still okay).
Any ideas? We're stumped.
