Tach signal - all the PSI literature for my conversion clearly says if you’re using the GM ECU tach output signal and an aftermarket tach - select the “4 cylinder” switch on the tach. However the tach signal from GM ecu is a 5V signal, so if your tach is looking for a 12v signal, an adjustment must be made. So in my opinion you have two mysteries to decipher - 1) exactly what is your aftermarket ecu outputting and 2) what is your tach expecting? A talk with DakDig may help, although I’ve found their tech help to be hit/miss.

My new crate LS3 is so quiet underhood you can hear the individual injectors clicking off at idle. There’s a reference point for you. Sounded to me like a “rattle” (more ominous) more than the noise a lifter/rocker might make. But vid/audio/internet recreations are notorious for not sounding anything like what you’re hearing with your ears.

 

I assumed he was using a factory ecu ?

Any decent aftermarket ecu you should be able to select the output for the tacho with regards pulse counts so any tacho can read correctly.

the fact his is working currently....assumes it is happy with the type of signal, just not the frequency of the pulses.

 

Not a factory ECU, it’s a MEFI standalone from turnkey engine supply that came with the engine I bought used.

Dropped the water I ran through the engine yesterday and replaced with coolant, it’s cold here and I don’t want to risk damage if the garage heater fails.

Ran the engine again to circulate the coolant, the fans kicked in, so that’s good. However I’m concerned about the top end noise.

The oil fill cap is clean as a whistle underneath, that’s doesn’t seem right to me, shouldn’t there be some oil splash under the valve cover? The oil pressure at idle is 2 Bar (30psi) however it doesn’t ramp up with revs, not good. What could be causing top end oil restriction?

Of course, might be worse case scenario. Someone may have offloaded a dead engine onto me. Totally possible with an unknown used engine. Everything is in place now, it starts and runs, all the supporting systems are setup, so a bare long block might have to happen. But, I need to figure out what’s going on first, I’d hate for it to be something with my oil line routing that’s causing an issue. Stumped at this point.

 

Contact whoever will be tuning your ecu, or the supplier etc. I would be amazed if you could not reconfigure the tacho output to make your rev counter happy.

As for the noise...without hearing it in person etc, just hard to say, but I wouldnt be comfortable driving it to see what happens.

 

Mine with 5w-30 oil will sit at 60-65 psig on a cold start - suspect that's where the internal relief is set. Drop to 35-38 psig at idle at 210F oil temp. And increases with revs. With oil temps at 210F, revs between 1500-2500 rpm I'm seeing 45-55 psig. Another data point.

As you said -- who knows what you've got with used motor. Hoping it's a simple non-issue. I went ahead and spent the money up front to avoid that.

 

Oil psi not rising with throttle is NOT normal. Anyway you could have pinched an oring? Though that being said, 30 pounds is plenty to keep that motor quiet. You may not wanna hear this but i got burned on a junkyard motor recently, it spun a rod bearing after about 10 miles. Noise sounded similar and i had 60psi. If its eating a bearing it should be in the filter for you to find, it will continually dump debris until the filter clogs or the bearing spins whichever comes first. Mine clogged 2 filters before spinning.

 

Cut filter open yet?

 

Not yet, probably this weekend. Too frustrated to deal with it for now.

At least all the development is done. If I have to buy a fresh long block it’s just an engine swap at this point and changing over accessories from one engine to the other.

 

Do you know whether the gauge/sender set up you're using has an hysteresis built in? Or, mechanical gauge?

 

This is the guage sender fitted to an adapter behind the intake, its a 2 pole electric sender. I'm confident the sender works, it was freshly installed on the stock 944 engine that came out of the car, it was accurate then and matches to the factory guage on the dash.

 

LOL - looks exactly like the VDO sender I’m using on the Volvo - one pole for pressure gauge and one for idiot light. Mine is “real time” - did the gauge show real time pressure fluctuations with previous motor? Just hoping maybe some “lag” built into the gauge might be behind your steady pressure readout.

 

You bet, real time fluctuations with the old motor. With the stock engine it was 5 bar cold startup, 2 bar hot idle, and moving between 2 and 5 on track depending on revs.

My logical side goes back to what 01ssreda4 said earlier, "30 pounds is plenty to keep that motor quiet" - yet it's not quiet. I'll pull the filter and have a look see.

If anyone has suggestions on a reasonably priced supplier for an assembled Gen III 5.3 or 5.7 aluminum long block I can swap in, feel free to post it up, I have a sinking feel that's where this is going to end up.

 

Might come out better financially buying a new crate 6.2L and parting out what you have.....my 10-30 year old Ford 5.0L part-out paid for about 2/3 of the new crate 6.2.....

 

That motor i had issues with, did not start rattling (lifters) until 5 psi. As the filters would clog (no bypass) the psi would drop and i would investigate. First time around I suspected a faulty sending unit so i checked with a mechanical gauge. I was getting some lifter tapping and turbo smoke at 5 psi but even then it wasnt terrible, but you could tell something was off. 2 filters later the rod bearing let go.

 

Well, I got my answer. The oil has enough metal sparkles in it to build another engine! The strange noise and low cold start oil pressure and unresponsive oil guage with revs turned out to be the worst case scenario.

I gambled on a used engine and lost. That's life. Not sure I'll bother cracking open this engine, may just hunt for a fresh built long block, I need something around the 350hp mark, more than that and the transmission won't take the abuse on track for long. Another aluminum 5.3 or possibly 5.7 long block. At this point at least its a more simple engine swap, everything around it is ready to go, wiring, fuel, cooling, accessories etc.

 

Bummer. In spirit of every now and then you have to say wtf - http://www.enginelabs.com/engine-tec...ock-is-a-jewel

 

Thanks Michael, appreciate the pick-me-up, although it might be too rich for my blood! It's a set back but life is too short to dwell on the little things, especially when I'm blessed in so many ways.

 

Yeah, that IS a jewel of a block! We can all dream...

 

Indeed -- most of us face a plethora of "first world problems".....the gym closes early the day before Thanksgiving - my life sucks!

My tongue was firmly planted in my cheek when I pasted in the link to the billet block. I still cast a non-binding vote for a new crate LS3, part out what you have. And deal with a weak transaxle when/if you have to.