That time of year has come for ice and snow and its time to start on my Z to do list. after about a year of daily driving, a couple upgrades and a clutch later with a wish list of goodies, I pulled my GTI out to bring the Z in.
I started just to check everything over to get a good scope of the engine health before next autoX season. compression tested at 130-135 psi across all cylinders. I notice the spark plugs were all pretty oily so I stuck a scope down the cylinders and all 6 had some degree of oil in there. so Im going to be doing valve seals soon. likely throw a cam in it but not set on any particular cams yet. dabbled the idea of pistons and rods while I have the down time but those may remain stock for now.
while Im in there I figured I would put fresh timing components, a water pump and gallery gaskets. if Im missing any other "while Im in this far" bits, recommendations would be appreciated.
also on this years to do list
*BC coilovers to replace the clunky current ones that came on the car
*solid diff bushing
*z1 engine oil cooler
*z1 oil pan spacer
*square 275/35r18 set up
*new rotors/pads (recommendations welcome) non brembo currently.

it also has a kinetic velocity manifold, ISR long tubes. dual HKS replica cat back, CZP throttle body and z1 adjustable control arms and tie bars
hoping this thing will be a ripper next spring season.

 

Hi Bologna,

130-135 psi seems a bit low, especially if oil is present to aid in sealing compression. Is this a built block for FI application (8~9:1 compression ratio)? I agree that the valve stem seals are probably shot and need replacing. I would recommend having a leakdown test done to confirm it's the cylinder head and not the bottom end as the source/cause of lost compression. It's good that the cylinders are all within 5psi of each other. FSM states ~200psi is like new, ~185 is average, and ~142psi is the minimum recommended.

Reason I bring this up, you have big plans for the engine/car. It would be counterproductive if the bottom end needs a rebuild/refresh (new timing components & cams specifically).

Before pulling the trigger, I highly recommend investigating a contingency plan on getting another shortblock or longblock lined up (used or rebuilt).
Cheers!
-Icer

 

thanks for the concern and advise. so far with oil pooling only in #4 and no fuel smell in the oil between changes I was never really concerned about the bottom end. with my tester I used its always read lower than higher end ones so as long as its been consistent I never gave it much thought. I do have a leak down tester so I might just do that for ***** and gigs before I start taking everything apart.
if that does reveal any kind of bottom end loss then I guess that makes it easier to decide if Im doing rods and pistons.

 

That's a good point! My OTC compression tester was giving me strange results (very lower numbers) after sitting in the box for years. The valve seals were dry, after cleaning and giving them a quick lube with some silicone, I got much more accurate results (higher numbers). In short, the tester valve for the gauge was leaking! Thinking about it, I'll probably need to replace the valve + seal the next time I use it (it's sat for another 7-8 years since last I used it).

Let us know what you discover after further investigation. If you have an articulating bore scope, I would do a closer inspection of the cylinder walls. Heavy vertical lines/scoring patterns is usually a sure sign that the piston rings are seized/shot and the bottom end needs a refresh (new pistons, rings, cylinder boring/honing, etc.).

Keep the thread updated!
Cheers!
-Icer

 

oil if pooling cause it’s leaking at the valve cover , then you pull the plug and it drains into the cylinder. I’ll bet you have oil on the non combustion chamber side of the plug

either way, that’s pretty low compression

 

Good Point Terrasmak. Personally, I always inspect my spark plug wells and suck out (or blow out with compressed air) any standing oil or dust/dirt/debris, before pulling the plug (on any car). Mostly because you never know what nasty could be lingering down there just waiting to fall into your engine upon plug removal! I thought this was standard practice for anyone wrenching on cars, but I'm sure some folks overlook/skip this step.
Cheers!
-Icer

 

the valve covers are good. I did double check the plug wells which were dry and would be irritating since I replaced the valve covers with aluminum ones last oil change.
anyway, I did a leak down this weekend and found cylinder 1 and cylinder 6 are losing about 25% and 20% respectively where the rest are like 10% at 70psi, thats as high as my harbor freight tester would go. so thats neat, looks like Ill be doing valves which also sucks because those headers were a PITA to install. on the bright side, bottom end seems to be solid and had no leaks from what I could tell. my biggest problem is "while im in this far"...

 

so I put my order in for all the fix it parts. Ive decided to say screw it and do bottom end, wiesco 11:1 pistons and eagle rods from CZP. Im curious regarding the cam. the tomei 266 duration is what Im looking at. I also considered the 274 and JWT c8 which is 272 if I remember right but for $700 more, I think Im going with Tomei. since its for an autocross and I wont be in the revs as much as on a legitimate track. the 266 I believe should be the better option if my understanding is correct about cams. anyone confirm this?

 

quick photo dumb from the past week. Christmas was a bit busy so didnt get to make the progress I was hoping for but happy how far its come with the limited time I did have to work on it.
having the front end off makes access to the headers slightly less miserable lol. still the worst part of the whole project so far.
I went with 11:1 compression pistons and the 266 degree cams.
dont mind the clamp Im using as a hood prop. its actually holding pretty solid.

 

Grab a 14mm torque adapter for the header nuts (something like ). That single tool, combined with a flex-head 3/8 ratchet saved me a lot of pain! Especially for the re-install of my aftermarket shorty headers. I didn't want to drop the coin on a full set, so I purchased the most commonly needed sizes on the Z33 (14mm & 17mm).

That's some good progress! Make sure your internal choices for the engine are spec-ed for the Revup VQ35DE. I'm not sure if that was mentioned before. I would be concerned about the cams being compatible.
Cheers!
-Icer

 

I use an offset 14mm wrench that works ok with some finess is all.
I made sure to get rev up specific parts if there was different options as well. so hopefully things continue to go smoothly.

 

timing cover off. looks like it was a little gunky but not too bad. I forgot about the bolts in the oil pan at first that have to come out, luckly I stopped and re evaluated before breaking the timing cover.

heads and cam caps all in good shape. no scoring, just a little more carbon build up

I was happy to see cylinder walls all still in nice shape




I hit it quick with a stone hone, making sure to keep it clean and trying to maintain that 45 degree cross hatching here. it was my first time trying this and there were no low spots or marks in the cylinders I had to fight with which was nice. I was pretty nervous going into this part

all the bottom end clearances appear to be within spec. I was hoping to have the rotating assembly back together this weekend but I spent a ton of time running back and forth to use the parts washer at work but at least now Im not putting grimy parts back together.

 

Really nice progress! That's actually pretty good for a Revup DE! I would have expected to see more varnish in the timing cover and more carbon build-up on the tops of the pistons.

Have you pulled any of the valves yet? I'm curious to know the condition there since that's the primary suspect in your loss of compression.
Cheers!
-Icer

 

to be fair I did run some BG EPR through it to help clean things before dropping the oil. the dealership I work at is a supplier so I run that every so often. wish I could have seen before and after which would have been cool.
I havnt pulled the valves yet, just looking at them in the head they all have a bit of build up. Ill be sure to post pictures when I do pull the valves.

 

I'm a fan of BG products. I run BG 44K through my cars once every year or two. I also use BG MOA frequently and I've tried EPR & ATC+. They're one of the few "snake oil" companies that I think actually works as advertised. But what's really impressive as of late is the Valvoline Restore & Protect. People are getting incredible results after running it for 10k+ mi.
Cheers!
-Icer

 

I have to say the demos they come do for us every so often to show that its not "snake oil" it is pretty cool to see how some of it works and they compare head to head with other brands to show a visual difference.

 

got to spend a little more time on project Z. a gentle reminder to double and triple check everything when assembling.. 1 step forward and 2 steps back..

got all the pistons tapped down into the bores and everything appeared fine. rotated the assembly after installing each one. after a few turns I noticed #3 had some nasty scoring. also found #1 had some scoring so I removed both pistons. lucky me at least its not bad enough to catch so I should be able to hone them out without much issue. I found #3 oil ring had a small piece chip off so new rings ordered. #1 rings appeared to be in good shape but still going to replace those as well. Im guessing the piston wasnt cleaned quite good enough before going in.. also pictured #5. that one looks ok so added for a glimmer of hope.



while Im waiting for new rings I decided to focus on the heads. removed all the valves and think I found where I was losing compression. I cleaned them up a bit with some scotch brite and wd40, plenty of pits on intake and exhaust side. after I cleaned them up I attempted to lap 1 of each exhaust and intake just to see. I called my local machine shop, turns out the 1 guy they have work there just had shoulder surgery. yesterday... so thats pretty neat. at least I have a few months before Im able to drive without 4x4.




so then I decided about the only other thing I can do which Im sure is everyones favorite part is cleaning off all the old gasket from the timing covers. gallery gaskets Ill fight with a little bit since those are really stuck on there. then I hurry up and wait. I guess I could keep myself busy cleaning up the wiring harness next.

 

Good catch on the cylinder rings. Did you check ring gap before installing on the pistons?

Yeah, those valve seats look pretty rough. Even after lapping they didn't clean up 100% or at least not my my own liking. I would for sure get them cut or replaced all-together. How did the valve stem seals look/feel? Was there excessive play in the valve guides?
-Icer

 

yes I did check end gap, the problem I figured was the ring compressor I was using which was one of those spring clamp ones. It appears the edge of one of the top oil ring caught and snapped off. this go around I ordered the solid Wiesco ring compressor that I thought I ordered when I got the pistons. anyway ring gaps are .33mm..ish according to my feeler gauge. scrapers are slightly larger, oil rings were all similar to the scrapers. I didn't have to file the gaps at all but I did deburr them all just to be sure.

I agree the valve seats looked... less than healthy.
the guy at my local machine shop is back part time for 2-3 days a week until his shoulder heals. I brought him the heads with old valves in their original spots and all the new stuff. He's going to try cutting the seats and valves to match the stock valves to hopefully not have to mess with the cam buckets too much.
alot of the valve seals were pretty toast.
I dont have a small bore gauge however when inserting the new valves in the old guides they all seemed pretty tight. no lateral movement that I could feel otherwise moves freely through the guides, with some lube of course.

I also got some cool new stuff today. I figured since the engine is already out and mounts were on my "to do eventually" list anyway. these were on sale from Z1. my wallet is in danger when there is downtime between the start and finish line lol.

 

Good stuff! Thanks for the update! Put a review out for the Z1 Poly Engine Mounts once you have some mileage on em. I purchased a set of the BDE Poly mounts when they were on sale some years back, but I haven't installed them yet, just sitting on them until my stock ones give out. Since my Z is primarily a street/daily vehicle, I'm concerned about the added NVH from poly mounts. I'm using the Gktech poly inserts for the stock transmission mount, and those strike an excellent balance between removing drivetrain slop without adding NVH.
-Icer