Loss of compression after long term storage

vulcan300 · 04-08-2012, 10:10 PM

Hello all,

I'm approaching the end of 3 long years of restoration on my 86 911 Targa and I've run into a puzzling issue.

When I started working on my car several years ago I had recently performed a major service which included a valve adjustment. The car ran great at the time and I even did a long road trip from Toronto down to Philly and back again.

I've had some recent set backs the biggest of which was a mouse that decided to turn my engine into a mouse condo. I found a huge nasty nest under the fiberglass shroud a few weeks ago, and cleaned it out. When cleaning up the engine compartment today I found evidence of more mouse nest material around the rear right plug. and when I pulled the plug I found the cavity above the oil cooler plugged with mouse nest as well. When I pulled the valve cover to clean out the nest I also found mouse nest material packed around all of the spark plugs on the right side! It's amazing where they are able to get to..

This all gives a little context on the state of things. Today I reinstalled the fan and alternator in a new Vertex alternator housing (which went in fairly smoothly). After tightening up the belt I turned the engine over to test the tightness of the belt. To my surprise it turned over very very easily.. I was able to turn the crank three or four revolutions before hitting the compression stroke. This was very different from my previous experience and it struck me as wrong.

I'm wondering what my next step should be. Should I do a leak-down test. A compression test. Perhaps both? What about removing everything above the block and head so I can get a look at the valves. Suggestions would be appreciated!

Digital K · 04-08-2012, 11:35 PM

I would dial it back a little bit and not worry about tearing anything apart. I am by no means an expert, but I wonder if after sitting so long, your rings aren't sealing properly. You might need to build some oil pressure and get some oil on the oil rings.

kuehl · kuehl's Garage

+1 on Digital.

Unless the mice are a new strain, a mix of Arnold Schwarzenegger's Terminator friends,
chewing on timing chains and cranks, just fire the puppy up and see how it runs.

If your really concerned, pull a few plugs on each bank and borrow a borescope and explore.

For the mice, during the winter, place socks filled with moth balls in engine compartment and smuggler's box, however you will have to vent it outside for a week before you can drive it in the spring, or place a time share swap ad in craigslist. "Cat wanted ......".

Tom '74 911 · 04-09-2012, 05:31 AM

Did you pull all the spark plugs and forget to tighten one?

KTL · 04-09-2012, 05:48 AM

Not uncommon for this to happen- compression loss. A long time mechanic and friend shared with me a fix he once did on a guy's Mercedes who was having a similar compression problem. Squirted a bit of ATF into each cylinder and voila' the compression returned. You just need to get a bit of oil in there to seal around the rings. Once the engine builds compression, it frees up the rings and everything generally returns to normal.

sam77rs · sam77rs's Garage

What I like to do is what I call a "Poor Man's Leak Down Test". Hook up a remote starter switch/button, so you can crank the motor over while you're standing by the back of the car. Have the rear wheels off the ground for safety, ie, on jack stands. As you crank the engine, put your ear close to the exhaust pipe and listen for air leakage through the exhaust valves. If they are not "shutting off", you will hear the hissing sound of the air. This would be a source of low, or no, compression.

When a 911 sits idle for several years, carbon in the combustion chamber can, due to soaking up moisture, crack and fall to the bottom of the combustion chamber where the exhaust valve is. When you crank the engine over, pieces of carbon can get caught between the exhaust valve and the seat, keeping it from closing all the way. Do not start the engine. You will burn a valve and cause bigger problems.

If the exhaust valves are good, then listen to the intake valves by putting your ear close to the air intake (take the air cleaner off). It is less likely that you will hear any problem with the intake valves.

If both of these tests are "good", then squirt a little oil (or ATF) in the spark plug holes (careful, not too much). Then crank the engine over a few times. Replace the spark plugs and start it up.

Don't forget to Have Fun in you Work Shop !!

scottb · 04-09-2012, 08:13 AM

Quote:

Originally Posted by KTL

Squirted a bit of ATF into each cylinder and voila' the compression returned.

I've heard that Marvel Mystery Oil is good for this, too.

vulcan300 · 04-09-2012, 10:27 AM

Thanks for the suggestions gents! I think the oil in the cylinder trick is probably the best way to start. I'd imagine if that doesn't fix the issue then the next suspect would be the valves. With respect to sam77rs's post, I'd think that doing a leak down test might be more effective to hear whether the exhaust or intake ports are allowing air to escape. Once the cylinder is under pressure I should be able to hear if air is escaping through the intake or exhaust.

If carbon has clogged up my exhaust ports, what can be done to fix the problem? Do I need to remove the heads and clean out the mess?

docrodg · 04-09-2012, 12:09 PM

Quote:

Originally Posted by scottb

I've heard that Marvel Mystery Oil is good for this, too.

+1 on Marvel oil. Known for freeing up "stuck" rings. 10cc in easch cylinder thru plug hole, crank a few times to distribute, then fire up and watch the smoke! This is a popular fix for some newer 4cylinder engines that are prone to having problems with ring seating.

Run a compression check, and a leakdown if you have access to the tools. Borescope can't hurt too. If compression is low or leakdown shows rings not seated do the MMO treatment.

tevake · 04-09-2012, 01:00 PM

Isn't there some fuel additive (tecktron or some such) that you can use to clean out the carbon deposits. I remember there was something to be used just before doing oil change that could clean out carbon deposits?

Cheers Richard

vulcan300 · 04-09-2012, 01:16 PM

Quote:

Originally Posted by docrodg

+1 on Marvel oil. Known for freeing up "stuck" rings. 10cc in easch cylinder thru plug hole, crank a few times to distribute, then fire up and watch the smoke! This is a popular fix for some newer 4cylinder engines that are prone to having problems with ring seating.

Run a compression check, and a leakdown if you have access to the tools. Borescope can't hurt too. If compression is low or leakdown shows rings not seated do the MMO treatment.

Unfortunately MMO can't be purchased in Canada as it's no longer sold here. Is ATF the best alternative? I just filled the car with brand new Brad Penn oil and would hate to foul it.

As for additives, I've heard that BG44K is a good one. There was a long thread on it quite a while ago. I also use Shell VPower as it doesn't contain ethanol and apparently reduces gunk buildup in the engine over time.

KTL · 04-09-2012, 01:22 PM

Can you get Berryman products in Canada? Their B-12 Chemtool is very good at getting rid of carbon deposits in the combustion chamber. I used it in one tankfull application on my '87 years ago and I was shocked how well it removed the carbon buildup on the exhaust side.

vulcan300 · 04-09-2012, 02:40 PM

Quote:

Originally Posted by KTL

Can you get Berryman products in Canada? Their B-12 Chemtool is very good at getting rid of carbon deposits in the combustion chamber. I used it in one tankfull application on my '87 years ago and I was shocked how well it removed the carbon buildup on the exhaust side.

The main active ingredients in the Berryman B-12 products are Mineral Spirits and Acetone. Acetone isn't seal friendly so I'm hesitant to put something like that into my engine. If there is something more seal friendly I'd be interested for sure.

On an interesting side note, I found an article about Marvel Mystery Oil being a potential reason for a small plane crash. Apparently someone mixed a high concentration into the fuel which cause the engine to cease functioning. One of the things that came out of the investigation was a list of components in MMO.

"The contents of Marvel Mystery Oil were 74 percent mineral oil, 25 percent stoddard solvent, and 1 percent lard."

I got a kick out of the "lard" component. I guess that was the mystery part

scottb · 04-09-2012, 02:56 PM

Quote:

Originally Posted by targamaniac

Unfortunately MMO can't be purchased in Canada as it's no longer sold here.

From MMO's website contact page:

Canada
Eastern Canada (Ontario, Quebec)
(905) 470-6665
Western Canada (Manitoba, Alberta, British Columbia)
(204) 334-6797

Maybe it's worth a call to see if it's sold there. Otherwise, ATF is prolly your best bet.

HTH.

docrodg · 04-09-2012, 04:08 PM

ATF is ok if you can't get mmo. Some people use mmo in the tank too so it goes thru the fuel system and cleans up everything (it does, but too much and it the car won't run right). I wouldn't do that on a Porsche tho.

KTL · 04-09-2012, 07:41 PM

Well the ingredients in Techron aren't all that great either. You're supposed to use it right before an oil change because it affects your oil.

Never had a problem with Berryman use on my '87 or my other vehicles I have used it. No fuel leaks or fuel-related problems ever.

There's all sorts of ingredients in products you wouldn't normally expect to see. Know what's a main ingredient in the famous WD-40? Fish oil. Aside from it's great perfomance in being a rust preventative, it's also a great bait spray for fishing!

Eagledriver · 04-09-2012, 08:28 PM

Just make sure you don't put too much oil into the cylinders, you don't want to hydrolock the engine.

-Andy

docrodg · 04-10-2012, 01:29 AM

Quote:

Originally Posted by Eagledriver

Just make sure you don't put too much oil into the cylinders, you don't want to hydrolock the engine.

-Andy

THat is why you crank a few times with the plugs out... then reinsert plugs and fire it up.

vulcan300 · 04-10-2012, 03:54 AM

Quote:

Originally Posted by docrodg

ATF is ok if you can't get mmo. Some people use mmo in the tank too so it goes thru the fuel system and cleans up everything (it does, but too much and it the car won't run right). I wouldn't do that on a Porsche tho.

Looks like I'll be using a little ATF then. Does the type of ATF matter? I think I have some synthetic ATF on hand.

vulcan300 · 04-10-2012, 03:57 AM

Quote:

Originally Posted by KTL

Well the ingredients in Techron aren't all that great either. You're supposed to use it right before an oil change because it affects your oil.

Never had a problem with Berryman use on my '87 or my other vehicles I have used it. No fuel leaks or fuel-related problems ever.

There's all sorts of ingredients in products you wouldn't normally expect to see. Know what's a main ingredient in the famous WD-40? Fish oil. Aside from it's great perfomance in being a rust preventative, it's also a great bait spray for fishing!

I know about the fish based origins of WD-40. It's interesting that both it and MMO have animal derived components.

As for the additives I understand that they all have to be pretty harsh to get their job done. I guess it is a question of how harsh. I had a look at some photos taken during a trial of BG44k and the results looked fairly impressive. I do have to take them with a grain of salt though since the testing was done by the manufacturer.