@“Propane Car”
Well, congratulation on fixing P0354
Good luck on P0304
More than likely it’s carbon build up on the back of the valve. Tom and Ray liked this stuff.
I see no harm in trying that product . . . it’s worth a shot
Now here’s a few questions
Are you thinking the carbon deposits are causing #4 low compression?
If so, why is the compression normal on the other 3 cylinders?
If OP used it, how long should he wait before performing another compression test?
I’d run a couple bottles through and try it after each tank full. If it’s working, you should notice a difference. Carbon on the back of any valve will cause low compression if the valve does not seat properly. It’s a cheap fix if it works.
What would a used engine cost to install vs. rebuilding? I would think that the Camry engine is pretty popular and you could get a decent used one. Just a thought.
Please tell me why carbon buildup on the valves would only lower the compression on #4 cylinder
There are intake and exhaust valves in each cylinder. Any valve in any cylinder can cause low compression in that one cylinder. It does not have to be in all cylinders.
What you are saying is not news to me
I’d just like to hear your explanation as to why carbon buildup would cause low compression in one cylinder only, and the others have absolutely perfect compression
I agree that using that stuff is worth a shot
But I’d like to hear your explanation as to why only the valves in one cylinder are affected to the extent that the compression is drastically lower than standard, while all others are perfect?
I thought maybe you’d tell me that it’s due to the design of the intake manifold, or something like that, but I’m not hearing anything concrete
No offense intended, I’m just curious
I would be more inclined to agree with you, if cylinder 1 was 150psi, 2 was 145psi, 3 was 150, and 4 was 120psi
But that’s not the case
If if were the case, I might think carbon buildup had caused lower compression in all cylinders, but #4 was the most affected
Assuming carbon buildup on a valve can eventually cause the valve to not close all the way, I can see how one valve would be the first to be affected. To me it would be very coincidental for all the valves to fail to close at the same time.
And for me it’s very coincidental for the other 3 cylinders to have perfect compression
Why would they not have perfect compression if the carbon buildup weren’t preventing those valves from seating?
If carbon buildup were a problem, and was causing drastically low compression in #4 cylinder, I would expect less than perfect compression in the other 3 cylinders
To me, carbon would build up slowly on all intake valves, not causing any valve to hang open. Then at some point, one valve would, by chance, be the first to fail to seat which would drastically lower compression in only that cylinder.
That’s the only way I know to explain it.
Well, I’ll believe that when/if OP posts pictures of massive carbon buildup on the valves
No offense to anybody, but I believe I have a right to be skeptical
I don’t think it is carbon build up either, but I would not be surprised if it has a burnt valve, most likely the face of the exhaust valve burnt off.
I am more inclined to believe it’s a burned valve, versus carbon buildup
Thanks for all the comments. I have read them all.
This car ran exclusively on gasoline from miles 0-100k. At 100K I added a sequential injection propane system. From miles 100K to 240K the car has run >90% of the miles on propane. You will not get the carbon buildup while running on propane. For the past 5K miles since I have had the check engine light I have been running on gasoline. I will try the cleaner but I am very skeptical that it is buildup carbon. I have taken apart a few propane engines over the years and I have never seen any carbon buildup on the internals.
I suspect that I have a burnt exhaust valve. To remove the intake, the air box and throttle body has to be removed. My inspection camera is broken so I will have to get a new one to see inside the intake port. The exhaust side should be fairly easy assuming no stuck bolts.
As far as getting a different engine, I am on the fence of doing this. The car is already high mileage and it maybe the case that the transmission, CV shafts, etc will start to fail. So basically, I could spend $1500 on the car and be up and going or i could use that $1500 + what ever I could sell the car for + 6-8K and get a decent used car with fewer miles.
I may just wait and look for something else out there and continue to drive my truck or motorcycle around while a good deal comes along or I have the time to remove the engine and get a rebuild kit. I have never rebuilt a small 4 cyc car engine before but I have rebuilt dozens of V8’s and motorcycle engines. The funny thing is that if this was one of my V8 trucks, I would have already fixed it. If this was one of my motorcycles, I would have already rebuilt the engine. Not sure why I am being such a wuss with this car. I am lucky that I have alternative transportation while I decide and or fix this car.
I just had an idea at how to blow some cleaner into the intake port without taking everything apart. I will just squirt some B12 through the propane injector port on the intake manifold.
You can get carbon build up in a propane fueled engine, just not from the propane. All modern engines have a PCV valve and if the engine develops enough blow by, the oil vapors sucked into the intake manifold will cause carbon build up on the intake side. Its more of a sticky very thick sludge rater than the hard gritty carbon you see on the exhaust, but it is carbon none the less.
I suppose after a while, enough of this would be sucked into the combustion chamber that it could build up the hard carbon on the exhaust, but I haven’t seen that myself…yet.