low compression fix

[randy merritt]

I posted this in my ongoing build thread, but thought I would post it here in a new thread because it was a real eye opener for me.

After I did a compression check, I discovered that Cylinder #1 had only 125 psi. All the others (except #6 which I did not check because of the annoying down pipe in the way) were right at 160 psi. I put about 3 tablespoons of oil in #1 and checked the compression again, but it made no difference. This lead me to believe I had a problem with the heads. The motor had no blow by at all. The truck still ran good, and did not smoke.

I put air pressure on the #1 cyl. at TDC, and you could clearly hear the air leaking from the exhaust. I assumed I either burnt a valve, or there was carbon build up on the seat.

The next day, I met with my buddy who owns a machine shop to see how much it would be to go through the heads if I brought one of them to him. He told me that it could just be carbon build up on the exhaust valve seat and to just spray water through the running motor. He said the steam generated by the water did a good job of cleaning out the combustion chamber. He said "I have seen a lot of problems fixed with a coke bottle full of water run through a motor". Well, I sprayed about a gallon of water through the motor by removing the air inlet at the throttle body and spraying it directly into the throttle body with the motor idling. I used a small pump up sprayer and sprayed a small amount at a time, letting the motor bog down slightly, then recover, spray more water, etc. I then retested the cylinder compression on the #1 cylinder. After running the water through the motor, the compression rose from 125 psi to 152 psi. I was shocked. The motor even seems to start and idle better, and it has more power.

This fix was much cheaper (free) and easier than pulling a head.

Tap Water. Thank you.
__________________

 

[atkonkler]

Re: low compression fix

Point taken , an old 24 ase cert mechanic told me of this year's ago and I forgot. I will be trying it soon thanks for the reminder! Good call!

 

[It's just a six]

Re: low compression fix

I posted this in my ongoing build thread, but thought I would post it here in a new thread because it was a real eye opener for me.

After I did a compression check, I discovered that Cylinder #1 had only 125 psi. All the others (except #6 which I did not check because of the annoying down pipe in the way) were right at 160 psi. I put about 3 tablespoons of oil in #1 and checked the compression again, but it made no difference. This lead me to believe I had a problem with the heads. The motor had no blow by at all. The truck still ran good, and did not smoke.

I put air pressure on the #1 cyl. at TDC, and you could clearly hear the air leaking from the exhaust. I assumed I either burnt a valve, or there was carbon build up on the seat.

The next day, I met with my buddy who owns a machine shop to see how much it would be to go through the heads if I brought one of them to him. He told me that it could just be carbon build up on the exhaust valve seat and to just spray water through the running motor. He said the steam generated by the water did a good job of cleaning out the combustion chamber. He said "I have seen a lot of problems fixed with a coke bottle full of water run through a motor". Well, I sprayed about a gallon of water through the motor by removing the air inlet at the throttle body and spraying it directly into the throttle body with the motor idling. I used a small pump up sprayer and sprayed a small amount at a time, letting the motor bog down slightly, then recover, spray more water, etc. I then retested the cylinder compression on the #1 cylinder. After running the water through the motor, the compression rose from 125 psi to 152 psi. I was shocked. The motor even seems to start and idle better, and it has more power.

This fix was much cheaper (free) and easier than pulling a head.

Tap Water. Thank you.
__________________

Nice!!
I take it you do not run water/methanol injection?

This would clean up your carbon build-up on the valves, pistons & combustion chambers, just an added benefit.

 

[mikew]

Re: low compression fix

Wow, never heard of this before. Is there a risk of damaging the motor at all?

 

[2500avalanche]

Re: low compression fix

Wow, never heard of this before. Is there a risk of damaging the motor at all?

Wouldn't the cool water crack the block if to cold?

 

[It's just a six]

Re: low compression fix

I believe guys have been doing this since the 50's?

No, it does not crack the block, it turns into vapor as soon as it gets to the combustion chamber.

If you add way, way too much water, you could hydro lock the cylinder & then KABOOM!:rant:

 

[tunerpike]

Re: low compression fix

Nice to know.. Thx for posting.

 

[randy merritt]

Re: low compression fix

Nice!!
I take it you do not run water/methanol injection?

This would clean up your carbon build-up on the valves, pistons & combustion chambers, just an added benefit.

I do run 100% meth injection, but I don't beat on the truck to bad, so I guess the carbon just built up over time.

 

[It's just a six]

Re: low compression fix

I do run 100% meth injection, but I don't beat on the truck to bad, so I guess the carbon just built up over time.

Ok, maybe adding a little H2O to your meth tank would clean it off better?

I had Julio (alky control) http://www.alkycontrol.com/ posts some pics of his combustion chambers & pistons after he tore down his engine.
They were really clean, but he also run s a lot of methanol & high RPM & high boost. Probably makes a difference?

 

[randy merritt]

Re: low compression fix

Ok, maybe adding a little H2O to your meth tank would clean it off better?

I had Julio (alky control) http://www.alkycontrol.com/ posts some pics of his combustion chambers & pistons after he tore down his engine.
They were really clean, but he also run s a lot of methanol & high RPM & high boost. Probably makes a difference?

I could add some water to the meth, but I assume I would need to redo my tune. The tune is dialed in real good now (thanks to Alex), so I didn't want to mess with it. I think I will just shoot some water down it about once a year. I have put less than 5000 miles on the truck in the past two years, so not driving it much (or flogging on it much) may promote carbon build up.

 

[Logan]

Re: low compression fix

Definitely an old school trick. My dad was telling me about this a couple of days ago. Glad to see you fixed it.

 

[dgoodhue]

Re: low compression fix

Just my opinion, I wouldn't mix water to your methanol. I would rather run some water through the intake once in a while.. You also use GM Top End Cleaner, that should get rid of all the carbon deposits.

 

[ajt86]

Re: low compression fix

I do this as regular maintenance on my cars, I suck a little but of GM top engine cleaner through a vacume line until it bogs down- usualy do a half a can once a year per car- if you check my pistons with a bore scope they always look brand new

 

[jamnut]

Re: low compression fix

Done that a lot, same thing if you take a can of Seafoam and run it through a vacuum line while the truck is running. I've seen some amazing things happen after running a can of seafoam through an engine. Just be ready to change the oil.

 

[It's just a six]

Re: low compression fix

I could add some water to the meth, but I assume I would need to redo my tune. The tune is dialed in real good now (thanks to Alex), so I didn't want to mess with it. I think I will just shoot some water down it about once a year. I have put less than 5000 miles on the truck in the past two years, so not driving it much (or flogging on it much) may promote carbon build up.

I would not flog it as much if you were to add some water to your meth tank, I am only saying to add a little not 50/50 mix that would throw your tune off some.

I am like you, truck is dialed in pretty good for 100% meth, so if I were to add water I would definitely not flog & ring it out sort to speak when running water, but remember H20 is great to suppress detonation also.

You never know when you forgot you ran out of meth, cant buy it that day or?

I am just saying it would be an easy thing to do is to just add water, no vacuum lines to disconnect TB hose, etc, & drive it around for a bit. Simple.

I had ran out of meth & had no problems running 70% isopropyl & 99% isopropyl alcohol.
Water & meth mix just fine & most water/meth system are designed to run both water & meth & are safer to use this way.

Sorry for the suggestion guys.

 

[randy merritt]

Re: low compression fix

I understand your point now, but in my case, I have an air to air setup, so it takes one clamp to remove the intake hose from my TB. I don't have to remove any vacuum lines or anything. Takes about 30 seconds.

 

[Snoman002]

Re: low compression fix

Been doing this for years.

Go run the truck HARD and long, get it good and hot.

Pull brake booster line, hover it over a large container of water or seafoam while giving it just a little throttle to keep it running. I have been known to accident I all dunk the booster hose in the water with no bad effects, I try hard to avoid that though.

Works the trick, and its a good way to clean the top end and the cat.

Make sure to take it for a long drive afterwards to get rid of the moisture.