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 Kiggly Racing
Please Support Fuel Injector Clinic

No compression on Cylinder #1

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.

turbotom

20+ Year Contributor
104
11
Sep 27, 2003
New Bedford, Massachusetts
Ok I was working on my buddies car and the car had BC280s which the car has been running great. Well noticed the top timing cover was chewing up on the timing belt so we decided to change the belt and change cams to HKS 272s because he didn't like having only top end power with the BC 280s, he wanted some mid range power as well. So after all said and done, I crank the engine over by hand and also with the ignition off and fuel off, everything worked out great. Timing was on the money. Start the car up, sounds funny and noticed cylinder #1 seems to have no compression.

Hooked up the compression tester and have 0psi of compression.

Did a wet test, 0psi.

Took both intake and exhaust rockers off, 0psi.

I used a buddies video scope and looked down the piston to see if they hit the piston and saw nothing!

Inspect the head gasket and everything seems fine, checked for loose ARP head stud nuts maybe loose, nothing which I haven't seen yet a arp head stud back off so i don't know.

Put the rockers back the intake side only to build up compression, 0psi.

4-3-2 have 155psi on the nose, to be running and now 0psi in #1 is weird.

The only thing I could think of is:

maybe the base circle of the cam is too big?

Too much carbon build up causing not to seat right?

Bad rings?

Bent valves?

I don't know this makes no sense how the car ran and now 0psi:notgood:

Well great minds come up with good solutions, my brain is burnt right now so any good advise would be great, thanks guys:thumb:
 
Do a leak down test to verify what is leaking. Sounds like the valves got bent installing the cams somehow.
 
Ok when you changed the timing belt, after you cranked the motor by hand, how long did you wait to make sure tensioner stayed in correct place. Also was the tensioner set correct could you pull pin out easy after. Did you guys bleed the lifters before start up, since you removed cams? Did you prime the oil system before start up? Most likely what happen is the lifters weren't bleed and you got lucky with 3 cylinders, but cylinder 1 wasn't so lucky and you bent a valve or 2 which would be the only way 1 cylinder would show up 0 on the test.
 
Took both intake and exhaust rockers off, 0psi.
This means either a valve is not sealing, or there's a hole or big crack in something vital.


maybe the base circle of the cam is too big?
(Edit -removed text, replaced with)
If you removed the rockers and still have zero compression on that cylinder then it's probably not the cam's base circle you should worry about.


Too much carbon build up causing not to seat right?
Possibly, not likely.

Not by themselves. There's more to it than normal wear.

Bent valves?
Very likely.

Like Bryan said, leakdown test.
 
Last edited:
Make sure you bleed those lifters! But there is some excellent advice in this thread. Bleed lifters, do a leak down test, and another comp test. I had a buddy recently bleed his lifters when he swapped in some 272's, cyl 1 only had 30psi compression. After bleeding the lifters, it went up to 170.
 
Delta, I have to disagree, if the base circle is too large, the HLA can not compress enough to allow the valve to fully shut. The base circle will have to be .030 or more to large, now on the other side about regrinds, the base circle is smaller and that is why the shims need to be used under the HLAs.


I will agree that the HLAs need to be bleed down and the leak down test run.
 
Correct. If the base circle is too large it will bottom out the HLA and hang the valve. Had a friend years ago put a Ranger cam in a Ford 2.3T and used the wrong lifters. Same thing could be going on with your mitsu. Not likely, but it could be.
 
Ok when you changed the timing belt, after you cranked the motor by hand, how long did you wait to make sure tensioner stayed in correct place. Also was the tensioner set correct could you pull pin out easy after. Did you guys bleed the lifters before start up, since you removed cams? Did you prime the oil system before start up? Most likely what happen is the lifters weren't bleed and you got lucky with 3 cylinders, but cylinder 1 wasn't so lucky and you bent a valve or 2 which would be the only way 1 cylinder would show up 0 on the test.

I cranked engine and let it sit for a hour because it was lunch time

The tensioner is in the right spot and no issues putting on timing belt and the pin was easy to come out so the tensioner is at the right height.

lifters where bleed before install

I prime the oil before start, and the car was running prior to changing timing belt

...................

I brought piston to TDC and added pressure to the cylinder to see if the rings were bad to hear or see and amount of air going pass rings and heard some type of air escaping but not sure where.
 
Well according to what you say you've installed everything correct. I would double check the lifters in cylinder one just to be safe. Well you know there's a leak so time to figure out what's doing it, you only have a few options. Do you have oem lifters or the revised ones?
 
if the base circle is too large, the HLA can not compress enough to allow the valve to fully shut. The base circle will have to be .030 or more to large, now on the other side about regrinds, the base circle is smaller and that is why the shims need to be used under the HLAs.


Correct. If the base circle is too large it will bottom out the HLA and hang the valve. Had a friend years ago put a Ranger cam in a Ford 2.3T and used the wrong lifters. Same thing could be going on with your mitsu. Not likely, but it could be.


I understand all of that well.

Do either of you know off the top of your head what the range of a DSM HLA is? Honestly asking.

If you have a base circle 0.030" too big (0.030" or 0.015" extra radius?), and assuming the HLA was originally shimmed to operate in the center of it's adjustment range, how much does that really change a DSM HLA's height during operation?
 
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