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BroncoBilt
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• Seattle, WA, USA |
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• Registered on 11/26/2014 |
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• 16 posts |
• 1 Vehicle
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 Posted:4/24/2015 22:39 |
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I just had my engine completely redone. Except for the block & heads, which I had done professionally, I did the rest of everything else myself. I installed a new oil pump, new rings, new main bearings, and a new timing chain/gear set... cleaned out the piston rings' carbon deposits. The surfaces of the pistons were perfect and there was no scoring on the skirts. The block was honed (not bored) and the heads were completely redone. Nothing was out of spec, and no boring or shaving was done, the machine shop guy said it looked "nearly brand new". Anyhow, got it together, and it runs very rough. It misses at idle, a lot. I'm in the process of figuring out why. No vacuum leaks. No smoke is coming out the tail pipe. No coolant or oil is being burned as far as I can tell. (smells really good) I tested the vacuum intake and it was very steady. No bouncing around. There is a strong "paint spray can rattle" sound coming from the side of the engine that has the low compression readings. The rattle goes away when the engine is under load, but is always there when not under load, from idle RPM (about 600) to 2500 RPMs. The KOEO and KOER report "no codes", everything is perfect as far as the ECU is concerned. It's a 95, and EEC-IV.
Today, I present "cold" compression #'s. I drove the car and shut it down at 4pm. I forgot to start and run it for a while, but I did a compression test at 10:30pm. It was still warm, but I don't understand hydraulic lifters: do they collapse after a while? do they plump back up almost immediately when I crank the engine again?
anyhow, here are the surprising numbers:
145
150
170
170
175
165
150
170
Each cylinder starts off at about 90-100, then goes up by 30 or so PSI per cylinder rev... I didn't put any oil in the cylinders...
any ideas? When I do a "warm" check, how long do i need to run the engine before I can start the test? I prefer not to burn myself...
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jdmeaux
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• Lafayette, LA, USA |
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• Registered on 1/5/2009 |
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• 525 posts |
• 1 Vehicle
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Posted:4/25/2015 06:03 |
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First, I am making an assumption that your reported compression is from cylinder #1 to #8 in order, which would show #1, #2, and #7 a little low.
Second, you report a "spray can rattle" sound from one side of the engine. Are you sure it is only on one side??
Hydraulic lifters are to be soaked in oil and compressed a couple of times in the oil to make sure all the galleries are full of oil BEFORE they are installed. Lack of oil will cause them to collapse and rattle. And also would give you lower compression results. https://www.youtube.com/watch?v=lorANZ1Tptw
Myself, I would pull the intake and replace the hydraulic lifters, following the procedure of soaking them overnight in oil, and use a pushrod to compress them a couple of times while IN THE OIL just before installing them. https://www.youtube.com/watch?v=KSljoewfKTc
*******************
PROUD MEMBER of www.crownvic.net
It's just a SUPER-DUTY Mustang GT Sedan. 198K miles and still rolling HARD.
1997 Crown Victoria P71 SVT *** ex-US Marshall service (the CAR)
STOCK?? I bet it was modified. 
13.26 @ 107.24 MPH 1/4 mi w/ me, tools, & full tank of 93 octane
I added CAI, NICHE 19 X 8.5 " wheels with 245/45ZR 19 rubbers, and completely rebuilt the front end with poly bushings, Kooks headers, 2 1/4inch exhaust, TCI 2200-2400 rpm Stall converter
.PLANS:: engine upgrade, 5.4L 2v stroker, rebuild interior in leather w/ buckets, thinking about turbos
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BroncoBilt
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• Seattle, WA, USA |
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• Registered on 11/26/2014 |
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• 16 posts |
• 1 Vehicle
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Posted:4/25/2015 12:30 |
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Hm. I never did compress the lifters before installing them. I was told by a few people, even the machine shop guy, that they will "fill right back up" when I put them in the car and run them. I guess I could pull everything back off and compress them... Hm.
I just re-ran the compression test, WARM, after the engine had heated up, with WOT
here are the numbers, by cylinder #, not firing order:
155 |
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BroncoBilt
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• Seattle, WA, USA |
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• Registered on 11/26/2014 |
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• 16 posts |
• 1 Vehicle
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Posted:4/25/2015 13:53 |
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hm, the post isn't editing right. I never did compress the lifters before installing them. I was told by a few people, even the machine shop guy, that they will "fill right back up" when I put them in the car and run them. I guess I could pull everything back off and compress them... would rather not.
I just re-ran the compression test, WARM, after the engine had heated up, with WOT, here are the numbers, by cylinder #, not firing order: 155, 170, 180, 180, 185, 175, 165, 180. I just put new rings into it, and just had the valves re-done. I'm thinking it MUST be the valve rockers, or the hydraulic lifters. The camshaft & lobes were in as-new condition, and the push rods were in excellent shape too.
comments?
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BroncoBilt
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• Seattle, WA, USA |
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• Registered on 11/26/2014 |
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• 16 posts |
• 1 Vehicle
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Posted:4/25/2015 15:39 |
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I just got done w/ the leak down test. What a pain... anyhow, here are the compression #'s (warm), followed by the leak down #'s for the same cylinder. The leak down #'s are reported as percentages of the input PSI that is being leaked. Input PSI was at 90.
cylinder - compression PSI - leakdown percentage
1: 155, 26% (seems like a lot)
2: 170, 23%
3: 180, 1%
4: 180, 2%
5: 185, 1%
6: 175, 7%
7: 165, 20%
8: 180, 1%
As you can see, the lower compression cylinders have a direct correspondence to the leak down test percentage being much, much higher. They say to listen to the leak of air from the air intake, from the PCV valve or the dipstick, or from the exhaust pipe. First off - how the hell can you listen to any leak when the compressor is going full bore, even if it's across the room? the thing leaks so badly, the compressor never turns off! I was able to prime the compressor and get a few second's worth of diagnosis out of just cylinder 1, and it's leaking from ALL of them. I hear hissing from the air intake, from the dipstick, and a faint rumble from the muffler, all the way at the end of it. Everything in cylinder 1 should be shut at this point, I don't know why I'm hearing any hissing at all, except perhaps past the rings makes sense. I just put in new Everything. I don't know how a few cylinders could be so off compared to the good ones. I'm stumped. One would think there might be a gasket leak between cylinder's 1 & 2, since they're both low, but the gaskets are brand new, the torque is right on the heads, and the deck of the heads was/is perfectly straight. I would also guess some kind of leak between cylinders 6 & 7 for the same reason. I guess I'm going to have to take off the valve covers and make sure the rockers are loose for these cylinders when they're at TDC before I can get freaked out and really, really mad at myself.
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