decarb loosen too much rubbish into cylinder chamber and cause loss of compression?

[MickLovin]

First up its a 100HP Chrysler 1979 model number 1007h9A. I know I probably am thinking too much, but after a previous thread posted, I am worried that my de-carbing of the motor has caused a loss of compression. I will explain why I think that, When I first bought the motor approxiamately 4 months ago it had 125psi on all but the bottom which was 123.
I had a problem first up with the fuel diaphragm leaking into the crankcase as it was severely cracked. I rectified this and the engine started nicely and ran well, I had the usual issues of it not being used for a while but finally knocked the cob webs out of her and she hole slotted nicely. Ok this is when it went bad, I did a de-carb on her a lot of stuff came out in the water of my esky/tank, the water was pretty clean still and after running it I left it for a while and later checked the water.
It had a lot of black pieces at the bottom which where when touched felt oily but still solid.

Question is have I done damage by decarbing it through the pug hole, see now I come clean, I put some de-carb in the spark plug hole, and now I am concerned I have sealed my own fate with my old girl. I still have to retest her as when I did the top two and they were 75psi on someone else gauge I stopped it at that, disgusted with the readings. So I still have to buy a comp tester of my own so I know it is a good reading. Please outboard gods let it be good sorry don't mean to blasfime.

 

[jerryjerry05]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

I decarb through the carbs and the plug hole.
I get the motor hot.
Then spray through the carb.
Then after a bit of spraying,shut it down and spray in the plug hole.
Let it set 24 hrs adding more de-carb as needed.
Then run and get it hot and do it again.

 

[MickLovin]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

That's exactly how I did it Jerryjerry, think i need my own comp gauge mate.

 

[jerryjerry05]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Like I tell everyone.
DON'T cheap your tools.
I paid $160 in 1986 for my comp tester.
It still works as good today as it did then.
You don't need to spend that much.
Mine is also for diesels and has a bunch of adaptors and a spiffy case.
"spiffy"=cool. just in case?

 

[Big Fish Billy]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

With that much carbon, there is a good chance your top rings could be cracked, especially with those low readings. Even if your "borrowed" gauge is a cheapy, as long as it's not leaking back, the readings may not be perfectly accurate but if some are 125 and some 75, it wouldn't be good. It may be worth it to pull the heads, check the gaskets, check the cylinder walls for scoring, the scores may be indicators of where the cracked rings are. Just some ideas....

 

[Jiggz]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

There is such a thing as over-decarbing. Remember, when you introduced that de-carb solution into the cylinder you are actually reducing the lubrication thus if done improperly or prolonged it can actually damage rings and cylinders. Although, I myself do the spray in seafoam into each of the cylinder, I only do this to soak it overnight but only one time. The next day de-carb starts with a warm up and then intermittent revving with no more than 2500 RPM on the muff. From there I just use the carburetor spray method, intermittently. I'll stop when very little amount of soots come out of the exhaust which should last no more than 10 minutes from the time I started the engine.

 

[Big Fish Billy]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

If you let the decarb solution, and I use Seafoam, I spray it in the carbs and try to stall the engine out with it...I only let it sit an hour, then fire it up, enjoy the smoke screen, and repeat the process until I get no smoke...usually it takes two to three times at most. Letting it sit for shorter periods, loosens the carbon more slowly and avoids releasing a multitude at once, which avoids the problem you mentioned.

 

[jerryjerry05]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Like Jiggs says,too much decarb can cause damage.
It strips the oil from the cylinder and bearings.

 

[hall832]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Spiffy Case

 

[jerryjerry05]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Mick's an Aussy and some of the terminoligy is a bit different(esky=cooler or tub).
I also didn't put this in.
The second time I decarb is through the plug hole only.
I get the motor hot and remove the plugs and load it up with Engine Tuner or Powertune.
Let it set for 24-48 hrs adding more if needed.
Then it's hard to start and I spay some premix in the cylinder after I clean the plugs.
Then I install new plugs if the comp is acceptable.

 

[mitchbuck]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Thanks for the info here. I rebuilt my carbs last spring and the engine ran great, but by the end of the season it was running rough again. Debating whether to take the carbs apart again to clean or just try some carb cleaner first using jerry's method. Though I'm a little nervous about potentially damaging the engine as well considering its a 1990 90hp....

 

[MickLovin]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Thanks for the info here. I rebuilt my carbs last spring and the engine ran great, but by the end of the season it was running rough again. Debating whether to take the carbs apart again to clean or just try some carb cleaner first using jerry's method. Though I'm a little nervous about potentially damaging the engine as well considering its a 1990 90hp....

Hi Mitchbuck, I would check all the lines leading to your carbs first and your tank, a lot of people like me when I first did it, start at the carbs, but a lot of times it isn't the problem, as the problem had started way before the carbs, for e.g. water in fuel tank with no water separator, no fuel filter in between pump and carbs, old fuel lines perishing from the inside, and off course the old fuel trick.

These are all things to check/fix before you even go to the carbs ( depending upon your familiarity to your motor and maintenance on it).
The after doing all this clean/soak your carbies, ultrasonic cleaners are good, then blow compressed air through them. After doing all this make sure you check orifices with a probe type tool.

Don't make the mistake I did and re-do my carbies over and over till I realised that firstly I didn't have a water separator on, my tank had crud and some water in it, and I didn't have a filter between the pump and filter. Since cleaning/checking/replacing these areas and then doing my carbies, I haven't had a fuel issue with it since. I have a 80 litre (approx 20 Gallon tank) and I took it out ran water and a degreaser in it, I let it dry out after rinsing out, then poured methylated spirits in it and rinsed out with metho. I also found my Fuel diaphragm perished and going through the carbies. So START at the TANK and work from there.

 

[mitchbuck]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Hi Mitchbuck, I would check all the lines leading to your carbs first and your tank, a lot of people like me when I first did it, start at the carbs, but a lot of times it isn't the problem, as the problem had started way before the carbs, for e.g. water in fuel tank with no water separator, no fuel filter in between pump and carbs, old fuel lines perishing from the inside, and off course the old fuel trick.

These are all things to check/fix before you even go to the carbs ( depending upon your familiarity to your motor and maintenance on it).
The after doing all this clean/soak your carbies, ultrasonic cleaners are good, then blow compressed air through them. After doing all this make sure you check orifices with a probe type tool.

Don't make the mistake I did and re-do my carbies over and over till I realised that firstly I didn't have a water separator on, my tank had crud and some water in it, and I didn't have a filter between the pump and filter. Since cleaning/checking/replacing these areas and then doing my carbies, I haven't had a fuel issue with it since. I have a 80 litre (approx 20 Gallon tank) and I took it out ran water and a degreaser in it, I let it dry out after rinsing out, then poured methylated spirits in it and rinsed out with metho. I also found my Fuel diaphragm perished and going through the carbies. So START at the TANK and work from there.

Thanks but I actually replaced the fuel lines 2 years ago from the tank all the way to the carbs and installed a fuel water separator in addition to an inline filter on the engine. My fuel diaphragm is also good. I was using a lot of starting fluid by the end of the season when it was cold and I know the stuff ain't good so wondering if carbs are gummed.

 

[MickLovin]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Oh well if you think it is the carbs and you have done the rest clean them and re sync them. Check compression as well, as it doesn't seem right you had to use starter fluid.

 

[ondarvr]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

If you didn't use the same compression gauge the readings mean nothing, and you only mention checking the top two cylinders, not the bottom one. The only way to tell if things might be OK to check all three and see if they are close.

 

[MickLovin]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Thanks ondavr, I have already come to the conclusion of buying my own compression gauge of good quality. It is a 4 cylinder and you are right I haven't checked the bottom 2 cylinders as I was concerned the gauge was wrong after only having the motor for a few months and seeing readings of 125 all round. go down to 75psi.
My further statements on the thread, were advising a hopeful answer to what they had asked. I am hoping in the end it is a gauge problem, possibly not sealing as well as the first gauge did. Thanks for your advice and it has been well noted.

 

[ondarvr]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

I just bought a motor from a friend that is a very good dealer, he checked the motor with his gauge and it was at 80 on each cylinder, I said I was shocked that it ran that well with such low compression. He said he didn't care what the reading was, only that they were equal. I pulled out my gauge and it read 120 on all three. I know how my gauge reads and what it means, he knew the gauge he used and what it meant. You don't have any experience the gauge you used to know how it reads.

Virtually all of the hard or semi solid gunk that comes out of a motor during a decarb is from the exhaust area, not the combustion chamber.

 

[Nordin]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

Mitchbuck, hard starting when the engine is cold sounds like the choke butterflies can be out of order. Check so they closes well all three.
It can be that simple but as you says it can also be low compression in cyl. 120 PSI and up and all cyl. almost equal is acceptable.

 

[MickLovin]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

I am only going by the specs of my motor, and I would say just because they are all even doesn't mean my motor is in good shape, yes it may start ok and run ok, but my specs for this motor read as 145 - 165psi, so if it is 75 in two or all of them, I can't imagine that to be a good reading, so yes I did stop when I only did 2 cylinders and I more than likely would have had even readings of 75psi on the 4 of them. What I am saying is I want to get my own gauge which I know how to use as I have had gauges before, but I want one with a correct reading, as I can't understand why you would get a 50psi difference between gauges 3 months apart with no use. And if it is only 75psi I will be looking at doing a rebuild.

 

[jerryjerry05]

Re: decarb loosen too much rubbish into cylinder chamber and cause loss of compressio

IF?? Maybe?? Possibly???
The gauge will tell.
The guage that reads 80 on all cylinders is a poor substitute.
To get a reading of 120 on all 3 or 4 is still low.
A good gauge is needed to take a reading.
It needs to give the actual reading.My motor specs at 145-155
If my motor actually read 125 on all 3 cyl.
I'd be freaking out and ready to take it apart.
If your motors "running" at 75# on the top 2 then I'd guess the gauge is at fault.
Mitch,do a comp/spark test before you do any damage or any more damage???