The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support STM Tuned
Please Support STM Tuned

1998 GST 6 bolt

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

To be clear, this was supposed to be a genuine Walbro 255lph pump #GSS342. It is correctly stamped with this part number on the housing, but the the logo is not designed right. The logo is faded from bottom to top, like a bad hand stamp rather than a hydraulic press, and the notch is missing from the bottom of the logo in the 'W'. It is also too squared at the bottom corners. Compare pics...
IMG_20200617_082042310_LL~2.jpg

Here is the real one...
Screenshot_20200617-084937~2.png

There are many other clues to spotting a fake. Another big one is the fake one has plastic gears seen inside the inlet tube. The real one has metal gears.
 
Had an oil leak at the turbo return line where it connects to the oil pan. Today I replaced it with a custom AN line that is flexible. The AN couplings are a little more restrictive than the inner diameter of the OEM metal line. I may order a larger diameter one in the future when I upgrade the turbo for better oil drainage. Good for now. No more leaks!!

IMG_20200622_162410480.jpg


IMG_20200622_143504045.jpg
 
Finally got my boost leak testing started today...it wasn't good...I knew it didn't run right (idle issues) and wouldn't hold boost but it wouldn't even hold 1psi on the test gauge when we pressurized the system...it was hissing loudly and leaking out the intake manifold gasket! Damn...tried tightening up the bolts but didn't help....so now I need to order a new gasket and replace it...
IMG_20200720_184636923.jpg
 
I ordered a premium intake manifold gasket that is metal with a sealing ridge and installed it today. I removed the coil wires, fuel rail, injectors and upper engine harness to access the upper manifold bolts easily. I reached underneath the manifold, on the driver side with a combination wrench to access the bottom manifold bolts.
IMG_20200903_104744620_LL.jpg
IMG_20200903_110020206_LL.jpg


After disconnecting some vacuum lines, throttle cable, harness clips, and throttle body bolts, I easily lifted the manifold out of the bay.
IMG_20200903_113713802_LL.jpg


I carefully scraped the old paper manifold gasket off with a razor blade from both surfaces. I noticed the old gasket was too large did not fit properly. It was from a 1g! Idiots....there is NO way it could seal. I want to go punch the imbecile who installed it....This was the cause of my major boost leak. This also explains why I could never get the car to idle properly!
IMG_20200903_121139936.jpg


The NEW metal 2g gasket looks like this:
IMG_20200903_121645924.jpg
 
Last edited:
You never know what you will find on these machines. I ordered some 2g intake gaskets (and 1g at the same time) from a well known vendor and got only 1g gaskets for different #'s. The gaskets were identical and definitely 1g.
Glad to hear there is positive progress!!!
 
Thanks! It's understandable if you order something and they send the the wrong part... or if the part you ordered is not described correctly, and does not fit your application. However if someone gets a 1G intake manifold gasket and then proceeds to install it on a 2G head they're an imbecile. The difference is plain as day. The 1g gasket will not even seal the 2g manifold due to it's larger sized portholes. Now it is fixed. While the manifold was off, I also noticed a frayed positive battery cable that is bolted to the starter. I'll need to replace that too.
 
Last edited:
So it turns out my intake manifold gasket was not the only source of the boost leak. With further testing I also discovered the fuel injector seals were all leaking, as well as the throttle body shaft seals, and the power brake vacuum hose from the intake manifold was also leaking pressure... It's a wonder I got this thing to run at all! So I ordered some new fuel injector seals and throttle body seals and I replaced the fuel injector seals today. So far, I have increased the idle vacuum from 8 PSI pre repair, to 15 PSI at idle.. It idles a little smoother now and I'm sure it will be even better once I replace the throttle shaft seals. Now it is actually boosting pressure up to 10 psi when driving. But I know that is still not high enough even for the factory setting. I will update soon!
 
In order to reduce the oil and combustion vapors being sucked into my turbo, I installed a nice looking two-way anodized catch can with a baffle inside and a little extra filter medium using a pot scrubber steel pad. This filter medium is securely sandwiched in the baffle and will not escape. The catch can mounts perfectly on the deleted upper cruise control module bolt hole. It doesn't hit the hood when closed, and it allows easy access for unscrewing the reservoir when it needs emptied. The threaded dipstick on top of the can is a great idea. This can is well made, nice design for the price and looks great.
IMG_20210327_113507449.jpg

IMG_20210327_113517269~2.jpg




I also put a one way 3/8" Kynar check valve in the PCV hose to eliminate the pressurized intake air being forced into the crankcase while under boost. The PCV valve is supposed to do this, but they tend to leak a little under boost, especially if they have some miles on them. The one way check valve still allows the engine vapors from the crankcase to be sucked into the intake manifold at idle and high vacuum, however it does not allow any pressurized air back into the crankcase under boost, and the Kynar material is resistant to chemicals, fuel, oils etc... I'll replace the hose with fuel grade when it arrives in the mail.
IMG_20210327_114356198.jpg
 
Last edited:
Update- I have modified the catch can setup so it's pulling vapors from the PCV side of the valve cover. The kynar check valve remains in the same place to prevent boost from going into the can and into the valve cover. The other nipple on the valve cover is feeding directly into the turbo intake pipe. I may get another catch can to install there later. I also replaced the dipstick since the old one broke at the handle. I installed a new Optima Red Top size 34 battery with 815 CCA. It's a little bigger than stock, but it's a good fit. Next project- new brakes and stainless brake lines!

View attachment 631332
 
Considering I bought the car in non running condition, it's been pretty reliable and fun since all the new parts have been installed... however, the full engine rebuild is being postponed as long as possible....it's still running good as is...I'm buying parts and getting ready for the rebuild sometime next year!
 
Just picked up a 1999 7-bolt 4G63 split thrust bearing motor with 112k miles, ready for a rebuild. Gonna get it taken apart and inspected soon, see what it will need...I kinda like the idea of keeping it around 350hp/ 300 torque to avoid breaking the tranny and try to get 30+mpg. Anyone recommend a good machine shop near LA, South Bay area LMK!

IMG_20210919_122742607.jpg
 
I installed a new oversized group 34 Optima Red Top battery, new battery cables, and a new AC/Delco starter this weekend. It was pretty simple, I didn't even need to get under the car. I just removed the battery and battery plate underneath it, and it was all easy access with a short extension and a socket!

IMG_20210928_073602653.jpg
 
Nice build man,are you going to do a stock rebuild on this 7 bolt or forged internals ?
I'm actually going to keep this 7 bolt a very modest build, because I already have a 6 bolt still in the car that I'll probably go a little heavy on the upgrades...when it's time comes...but she's still running good for now! So I'm thinking mostly stock on the 7 bolt, sans the results at the machine shop... something semi-quick, economical and reliable...that won't break the bank OR my transmission...
 
I picked up a half molested and parts missing '99 gauge cluster for free and removed the gauge faces to switch out with mine. It was tricky, but I found a really simple YT video using two spoons to remove the needles carefully so I could swap the overlays with mine. It was a good opportunity to replace half dozen burned out bulbs too...it turned out pretty good...the '99 cluster silver faces are a good match with my silver AutoMeter Pro Comp Ultra Lite gauges, and the '99 faces look great at night ..the only problem I had is putting the needles on exactly as they were...turns out they were all off a bit, so I had to remove the cluster several times after driving the car for awhile to check them... and then go through the whole process of removing the cluster and taking off the clear cover, remove the needles and change their position and put it all back together again... Now I have the tach, fuel, temp gauges all pretty accurate...The speedo still reads 11mph too fast, so I'll have to pull the needle off again a few more times ..but overall it was a good FREE upgrade!!



IMG_20211219_122311.jpg


IMG_20211219_144505~2.jpg
 
Last edited:
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top