Back Story: Blown head gaskets and leaks everywhere. Had shop clean and inspect long block, deck heads, hone the block, replace all bearings, gaskets, seals, PISTON RINGS, and VALVE SEALS. Been running on Royal Purple 5W-20 break in oil for 150 miles now. However, over tightened oil pan gasket started leaking.

Symptoms: Gasket leak was not "leaking" but instead it was "spewing". Small rear leak caused oil over the entire tranny and trans box, all the way back to rear axle in just 15 miles. Also started to think I had a blown head gasket already because of oil found on block edge where serial # is. Come to realize it's oil seeping from dip stick. Also, puffing smoke from PCV outlets and oil fill hole when opened.

Consensus: Too much crankcase pressure from blown piston rings or valve sealing.

Testing: Ran two compression tests; one cold & one hot

Cold Test:
1- 141................2- 139
3- 144................4- 140
5- 145................6- 137
7- 129................8- 142

Hot Test (between 185*-175*):
1- 146................2- 136
3- 139................4- 148
5- 150................6- 130
7- 146................8- 138

With 6 as the lowest number (14% deficiency/ 20psi from max), I added a teaspoon of oil as a check and it rose to 155.

At idle, it doesn't feel completely smooth. Every half second it has a minor decrease in "power" or "sound". Not sure how to describe it. I am still learning as I go, but I've read two different opinions on how much the numbers should vary (low and high within 10% OR high and low within 21psi). I'll take any and all opinions. I'm just trying to learn as much as possible and ensure it's good before I even think about letting my wife drive it. Thanks!

BTW (I'll put this in here instead of new thread), the spark plugs are clean and "white-ish" suggesting lean mixture. Is that common?

I'm also battling a high idle (1200). Throttle valve is set per the rave. MAF and intake have been cleaned. New IAC. Coolant thermostat reads correct. But IAT temperature is off... For instance, surrounding temperature yesterday was 74, but a scan of the nipple on the end of the IAT had it at 82. Does that suggest anything? Thank you!

 

I don't know how many miles on the block but instead of a hone it should've been bored because rings don't like ovals. The idle needs a reset by a shop that can access the ECU. Plug color is fine but yes it's lean. Get the idle fixed and that will change. You have one cylinder out of eight I'd consider decent. I have a 94 four banger pushing 180 per cylinder average with 172k, all original except the timing chain.

 

I just read in the rave that the 9.35:1 should have compression around 170-180 psi... Dang.

ihscouts- you think I should pull it and redo it or call it good enough?

 

Your blowing by allot so maybe with thicker oil that may cut back but it aint great and your idle will be lumpy as hell even when set. Did you set the rings on first fire up with high rpms? Did you measure your ring gaps before installing on the pistons or just wrap em on the slugs and call it? I hate bearing any news that's not happy news..... but man, all that effort to come up short is just as hard for me to swallar as it is for you. If your readings where higher like in the 160 range I'd call it. How about the heads, you say you had new seals, did they do em? Did they leak check the valves? This is about calling it good or a redo......

 

Everything was done by a machine shop. I took him the long block and all the new parts. Told him I wanted a full rebuild to last another 100k miles. He told me he would take care of everything. When I picked it up he said all was set and should be good to go. I know that I can take it back to him and the services should be free but it's the cost of parts and having to do the work of pulling it... Either way I want it to be good for a long time.

I didn't specifically try to set the rings but the idle was very high at 2k rpm for about 5 minutes on first startup

 

Well then it should be taken back and looked at. The rings should've sealed within ten minutes and for sure by 150 miles. Does it smoke?

 

Slightly yes. I will take it back to him, but I just like to study up and know options before he tells me his plan. I struggle trusting other shops because I've dealt with lying shops before... Thanks for the help

 

Press em hard to do the right thing. Let the motor do most of the talking.

 

Oh I will, but first I have to know what the right thing is, in order to push for it. Is there somewhere I can buy over bore rings? I have found them for the 3.5 & 3.9 but not the 4.0...

Disregard, I've now read that we can bore up to .010 without having to change pistons or ring size.

 

I had a bookmark on aftermarket performance pistons (lighter and balanced) for the 4.0 but can't find it...... swapped everything over from a now retired laptop, still mopping up.

How many miles on the engine at rebuild? Any overheats (that you know of) prior to yours?