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Discussion Starter #1
I’m so bummed... I finally got around to taking on a project I was planning when I bought my ‘92 VR4. The scope of my project was as follows for the purpose of making the VR4 well maintained, reliable, and smog legal. Here was the scope of my project:
  • Pull & paint valve covers; replace all valve cover seals
  • Remove and polish upper intake plenum; replace gasket
  • Run compression test on all cylinders
  • Remove cams and replace valve stem seals
  • Install gen 3 lifters
  • Inspect timing belt & tensioner; replace belt depending on condition
Here are the results of my compression test:
5 - 150
3 - 138
1 - 152
2 - 155
4 - 150
6 - 50

I placed some oil in #6 cyl. And the reading went up to 70 ~ I was a bit shocked as my car makes very good power. I plan to check timing and do a leak-down Test, but all indication so far are compression rings or cylinder wear.

So, as I see it my options are:
  1. Pull & rebuild my existing engine (I assume it’s a gen 1 2-bolt block with cast iron crank
  2. Find a gen 2 4-bolt block with forged steel crank to rebuild
  3. Buy a used JDM or other domestic running engine and install it.
While I wasn’t planning to have to spend time and $ to repair such a significant problem at this time, my tendency is to build a solid foundation for future performance increases, so a Gen2 4-bolt main with a steel crank is what I’d like to find.

What option do you guys recommend? Do any of you guys know of anyone selling a gen 2 4-bolt long block - Either running or rebuildable? Any significant issues installing a gen 2 engine into a gen 1 VR4? I am running a stock 5-speed which pops out of 2nd gear. I’d be willing to change to a 6-speed unit depending on cost and what issues that swap might create... Any insights and advice is greatly appreciated!
 

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yup, and if the valve cover is off you can more easily see valve position when doing the leak down.
 

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Discussion Starter #4
Ok so I completed a compression leak-down test today. I have 78% leakage from no. 6 cyl! All others are between 10% & 15%. My evaluation of the leakage source shows air-flow into the crank-case / valve covers. Considering the source of the leakage and the fact that compression increased with the addition of oil into the cyl., my conclusion is that the piston rings are shot and / or my #6 cyl. wall is damaged or worn.
 

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a bent or stuck valve(s). did you have the valve cover off during leakdown test? cylinder #6 often runs lean so i may also suspect a damaged compression ring on the piston.
 

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Discussion Starter #6
Well gang... I did an exhaustive search on the 3si.org forum last night searching for similar conditions to my very-low cylinder #6 compression and found several threads from our fellow enthusiasts with the exact same condition over the years. What I can conclude is that #6 cylinder has a tendency to run lean on our platform, especially under higher boost and stock fuel delivery. In fact there are a few posts showing pictures of their granaded #6 piston where the compression ring seat on the stock piston cracked and disintegrated. As I only bought my VR-4 a few months ago and was told by the seller the car was smoking and would not pass smog due to valve seals, I took a chance on the car without thoroughly testing the engine... It's unfortunate, but LET MY MISFORTUNE BY YOUR GUIDE ~ Never buy one of these cars without at least doing a FULL compression test of all cylinders! Any cylinder tested under 125psi YOU SHOULD WALK AWAY! Or at least know that anytime you need to pull the engine you could easily spending $2k minimum plus your time! (I.e. You will fix the immediate problem plus do a timing belt and pulleys, water pump, and have a shop test your heads and possibly do a valve-job).

I am left with the option of trying to recoup my $4,500 by parting out the significantly modified VR-4, or dumping ~ $2,500 into a short-block...
 

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Money pit owner.
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damn, that is the worst case scenario.

was your car modded? or did it have stock turbos/fuel system? you can put a bore scope down #6 and check for piston and cylinder wall damage versus bent valves.
 

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Discussion Starter #8
damn, that is the worst case scenario.

was your car modded? or did it have stock turbos/fuel system? you can put a bore scope down #6 and check for piston and cylinder wall damage versus bent valves.
Interestingly enough, my VR-4 has lots of mods: suspension, exhaust, Intercoolers & pipes, breaks and calipers, two-piece drive shaft, 4-core aluminium radiator, fuel-pump, regulator, and rails, Jester ECU (set to stock '99 tuning), but has stock turbos, injectors...

I actually like this configuration (for now) as my son & I are planning to auto-cross and road-race her and I really don't need a lot more horsepower to run in these events. I'd rather focus on fine-tuning the suspension and running reliably before running more ponies. This will also make us really learn to drive and not always overcompensate with horsepower...

I like the idea of doing a bore-scope... Any ideas where I may find one? I actually didn't take off the back valve-cover when I did my leak-down test. I plan to do this as I'd like to confirm that the #6 cylinder valves are moving correctly. This scope would be the final test...

BTW - I'm pulling the trigger on a 2-bolt short-block today with forged pistons, rods, and gen2 crank!
 

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Its odd that a stock motor/turbo/fuel car leans out cylinder #6 but I've read the same threads as you about that issue. Maybe your Jester ECU is flashed with some different boost/fuel/timing map. I did the IMR stainless steel fuel loop on my car stock car because I've read that stock fuel loop is to restrictive.
I bought an inspection camera from Harbor Freight long ago. https://www.harborfreight.com/plumbing/plumbing-tools/inspection-cameras.html

Supposedly there are new USB cameras for your smart phone too.

Cameras do have a hard time looking "up" at the valves.
 
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