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Old 01-09-2008, 04:02 PM   #1
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Default leakdown test bad, what should I do?

This is my first post. Been lurking for months.

I bought a clean ‘94 with 90k miles a few months ago. I had my credit card out and ready to order the BEGi S kit but I decided to first do the basic diagnostics…

Compression test was: 175, 165, 165, 170
Seemed good enough.

Vacuum was 18 in at idle.

Timing is 14* and I run 91 California crap gas. Runs good.

Then I did a leakdown test. The leakage was equally terrible in all four cylinders. The leakage past the rings was so bad, I could actually hear the oil gargling through the dipstick tube (with the oil filler cap in place).

I burn 1qt of 20w-50 dino per 300 miles and the oil turns jet-black within 50 miles. I’ve tried 6 or 7 different oils and weights with similar results.

I don’t think this motor qualifies for a turbo.

Power goal: If I had to state a power goal, I’d say 250whp. Doing it in steps would be fine.

Budget: If I had to state a budget, I’d say $7k.

If you’ve made it through this long post, thank you. My reason for posting is to get advice. I’m not quite sure what to do.

My original plan was to:

1) get bigger injectors, MSPNP and wideband installed. Sort out the timing and fuel.
2) then install the BEGi S kit.
3) then upgrade gradually.

But it looks like I need to rebuild/replace my motor first.

With my budget and hp goals, should I:

1) build a stout shortblock (forged pistons/rods) and port the head and extrude hone the intake? After machining and parts, that would be at least $3k, correct? Leaving me with $4k for other FI parts…

2) Or should I find a low mileage long block, leaving me with more cash for better FI parts?

3) Leave it as-is and boost it with crappy rings

Thanks guys. I’m open to ANY and ALL suggestions.

Chuck
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Old 01-09-2008, 04:16 PM   #2
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i was in the same boat as you, i bought a parts car with good motor and swapped the motor and tranny out. once i finish boosting it i will start a complete build on my old motor and once done swap back and turn up the boost

if you choose the rebuild route, leave the head alone for now and just rebuild the bottom yourself
CAT rods-$320 appx.
stock pistons ok at those levels so maybe just some high quality rings and call it a day
keep in mind you will need a strong clutch, like Clutchnet or ACT for those power levels, might as well do that first after the MS and WB and Injectors...

make sure to replace all seales when redoing your block, a new timing belt and WP would be a good idea as well
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Old 01-09-2008, 04:16 PM   #3
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What were the numbers for the leakdown test? Those are pretty good compression numbers for a terrible leakdown test.

Personally I would boost it as is. Be prepared for your dipstick to pop if you're going to run high boost but otherwise it wouldn't bug me.
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Old 01-09-2008, 04:22 PM   #4
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Weird that the leakdown test was so bad and that much oil consumption with a pretty normal compression test. I'd have thought that the compression test would have been much lower.

Anyway, if 250hp is your target, then you don't "need" a built motor. It's always nice to have for the safety and headroom for more power later.
You can probably source a low-milage 1.8L with good compression for ~$500 and have more money left for other go fast parts, but the power bug is worse than crack so tough call.

If you can find a reasonable priced replacement engine, I say get that and swap it in to get your car turboed sooner (so you can enjoy...now!) and then rebuild your current engine on the side slowly for later when you want more. If you can't find a 1.8 engine in good shape for a decent price then you go built.
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Old 01-09-2008, 04:40 PM   #5
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Yeah, those compression numbers look good to me for 90k. Figure half of that is leaking past your valves given the miles.
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Old 01-09-2008, 04:42 PM   #6
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Quote:
Originally Posted by xveganxcowboyx View Post
What were the numbers for the leakdown test? Those are pretty good compression numbers for a terrible leakdown test.

Personally I would boost it as is. Be prepared for your dipstick to pop if you're going to run high boost but otherwise it wouldn't bug me.

mine lasted for 2 years boosted with similar compression/leakdown/consumption. but then one day the piston melted. no fun. do it right the first time.
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Old 01-09-2008, 04:46 PM   #7
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Search out a thread by "SamNavy" he had a build vs swap used motor discussion for his similar situation. I chose the "stout" route... never regretted it. With a 7k budget its well within your reach with some change to spare. Basic bottom end parts were something like 800-900 bucks (pistons/rods/gasket/ARP studs). Add in some machine work, and in the future you will be have that wonderful feeling of security, as opposed to the "oh **** it may blow" mindset
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Old 01-09-2008, 05:29 PM   #8
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I had a similar problem, only mostly limited to cylinder 3. I put the 94 motor in the garage and bought a used 2000 motor. Someday I'll build the old 94 motor, and run the 2000 head on it.

-Mike
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Old 01-09-2008, 05:35 PM   #9
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Great help guys. Thanks.

To those who asked, I think the reason my compression numbers were good despite the worn rings was due to carbon buildup. Looking through the spark plug holes, I see LOTS of carbon in all cylinders. And all the oil I'm burning probably compounds that issue.
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Old 01-09-2008, 05:36 PM   #10
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Stick with your plan, get to know boost and EMS, and start thinking about a replacement bottom end. That way, if you screw something up while you learn MSnS, no big loss.
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Old 01-09-2008, 05:37 PM   #11
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oil additive.
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Old 01-09-2008, 06:00 PM   #12
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Brain,

additive reccomendations?
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Old 01-09-2008, 06:22 PM   #13
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one of those super duper stop leak ones.
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Old 01-09-2008, 06:51 PM   #14
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that engine restore crap in a silver can seemed to work great on my buddies old school trooper. stopped the oil consumption for nearly 40K miles when it spun a bearing (275K when it died).
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Old 01-10-2008, 11:20 AM   #15
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Quote:
Originally Posted by Braineack View Post
mine lasted for 2 years boosted with similar compression/leakdown/consumption. but then one day the piston melted. no fun. do it right the first time.

I ran my talon for over 3 years with 115 compression and as much as 85% loss in the cylinders (some were worse than others). No problems. Only pulled the engine, because I picked up a miata to roll in while I tore the car apart. That kind of leak issue shouldn't result in engine loss, just power loss. Things will be a little less responsive, but the physical components should hold together all right.
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Old 01-10-2008, 12:36 PM   #16
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I have similar compression numbers but I haven't done a leakdown test yet. My car is currently undriveable with the exhaust manifold and downpipe pulled, waiting for my BEGi kit to arrive.

Could I do a leakdown test now, while I'm waiting for my kit to arrive?

Also, do leaks in the vacuum lines affect the leakdown test?
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Old 01-10-2008, 12:38 PM   #17
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yes. no.
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Old 01-10-2008, 01:01 PM   #18
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I had similar results, but low compression in cyl 3-4, but I did not even bother with a leakdown since I was burning 1qt. of oil per 100 miles. I say build it stock with the cheap H-beam rods.
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Old 01-10-2008, 01:25 PM   #19
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Aight. Anybody know where I can source a cheap compressor that can do a leakdown test? I mean, like, cheap. Someow I think that the ones over at my local Home Depot are a bit overdoing it.
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Old 01-10-2008, 03:19 PM   #20
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xveganxcowboyx and Brain,

It sounds like you guys both ran FI on motors that had serious sealing issues.

I assume blowby and oil consumption were bad?

Did those two factors make for a difficult tuning situation?

What does burning lots of oil do to the WB signal?

Thanks
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