Welcome to the North American Subaru Impreza Owners Club Thursday March 28, 2024
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 05-15-2021, 04:52 PM   #1
undyjr
Scooby Specialist
 
Member#: 459692
Join Date: Dec 2016
Chapter/Region: South East
Location: Hampton Roads Va
Vehicle:
2019 WRX STI
silica black

Default valve lash

I appreciate everyone taking the time to read this. I had a machine shop that has a Subaru head specialist install Manley valves into my EJ257 heads. I checked the valve lash after the heads had been torqued to my stage 2 IAG short block and all were right at the tightest tolerance and just below. As I recall most of them were right at max tightness. Whether or not it was the right decision I sent it.

Fast forward 1100 miles to my pre-dyno inspection and I failed the leak down and the compression (mainly due to a cylinder imbalance) I'd like to add that although I was on a break in map the car ran great. I even snuck in some waste gate pressure boost with no knock. Here are the numbers:

Compression
#1 141psi
#2 157psi
#3 150psi
#4 146psi

Leakdown (hot)
#1 14%
#2 8%
#3 13%
#4 15%

Leakdown (cold)
#1 12%
#2 9%
#3 11%
#4 14%

I pulled the valve covers and checked the valve lash on a cold motor.

According to the FSM the tolerances are:
Intake .20mm +/- .01 Exhaust .35mm +/- .02

Cylinder #1 Intake .15 and .15 Exhaust .30 and .30
#2 .15 and .13 .30 and .28
#3 .20 and .20 .30 and .33
#4 .18 and .16 .30 and .30

Here are my questions. Do these lash measurements require new buckets? Do they explain the leakdown results? I'm confident I'll be able to change buckets with the motor in the car. Why did the lash change so much between assembly and now? I'm expecting responses to range from "send it" to "pull the motor and send the heads back to the machine shop". Ultimately I'll have to decide what to do. I can say there are a select few that I highly respect and I look forward to their input. Thanks again for reading.
* Registered users of the site do not see these ads.
undyjr is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 05-15-2021, 07:30 PM   #2
junebugfareast
Scooby Newbie
 
Member#: 167468
Join Date: Dec 2007
Chapter/Region: TXIC
Location: H-Town
Vehicle:
2004 STI
White-ish

Default

The leakdown test might allow you to understand where the air was being lost to. Either out the intake manifold/inlet, block/oil filler cap, or exhaust manifold.

However, those stated lash clearances will not impact a cold leakdown test. Bets are off on a warm motor. Losing that much lash in 1000 miles is suspicious. Valves or cam lobes are wearing? Valve seats being driven into the head? Spring binding?

If you want the lash to be at spec, you will have to buy buckets or possibly exchange at least some of them between valves to get the desired clearances. Life is like a box of chocolates on the buckets you have - you never know what you will find until you remove them and turn them over.

Whoa on changing the buckets in the car. Consider that there is very little clearance between the frame rail and the cylinder heads. The cams must be removed to change buckets. I've never done it in the car, but I suppose some have. Just a lot of work.

I suspect you have some sealing issues on the rings. However IAG states something like 3000 miles until the engine is as tight as it is going to get. I can't comment whether that is more a marketing number or an experience based number.

I wouldn't pull the motor until you had a better idea what is going on it.

I don't know if you intend to make a warranty claim at IAG. I guess asking them first what they will want to have done before you ship the block would be a good place to start.
junebugfareast is offline   Reply With Quote
Old 05-16-2021, 11:43 AM   #3
undyjr
Scooby Specialist
 
Member#: 459692
Join Date: Dec 2016
Chapter/Region: South East
Location: Hampton Roads Va
Vehicle:
2019 WRX STI
silica black

Default

Update:

I decided to do my own compression and leakdown test. The tests were performed on a 71 degree engine. Cylinder to cylinder variance was my primary concern during the compression test and as far as the leakdown numbers I will defer to more experienced members for input.

Compression test:
#1 115#s
#2 121#s
#3 115#s
#4 119#s

Leakdown test at 80psi :all were between 10 and 11%


At this point I'm inclined to put another 500-1000 miles on the motor and perform the tests again.
undyjr is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 10:50 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission
Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.