No compression in 3rd & 4th cyl why?

4runnerNB · 11-15-2009, 05:19 AM

I was throwing a Coolant Temp Sensor signal for a few days and it would occasionally cause the engine to buck a couple times, then the light would go out and it would run fine, except when it did that and I was waiting at a stop light and it would stall out and you could smell lots of gas. I'm guessing the sensor floods the engine with gas when it gets a bad signal and it washed out my 3rd & 4th cylinders? Is that a good guess?

I lost those two cylinders all of sudden and was still able to drive it around 30-40km/hr but it was knocking bad. We took the plugs out and 3&4 were black and the compression test confirmed the cylinders were not getting compression. One mechanic I talked to mentioned that cam could have broke in two.

So, should I get a used engine and drop it in or is there anything I should check on first to see if there is an easier/cheaper repair?

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peapicker · 11-15-2009, 07:56 AM

my 2 cents. Im a fan of rebuilding what you have. When done you know exactly what is in your engine and what kind of shape the internals are in. when a used engine is bought, its just a guessing game as to how dependable it is.

thook · 11-15-2009, 11:56 AM

Cam breaking in two seems rather unlikely. But, you could always pull the valve cover off......pretty easy........and have a look. It's right there on top. I'm assuming 4cylinder?

If the coolant temp sensor goes blah, then yeah......your motor will flood. Seems odd to me that it would only flood on two cylinders, but then I'm no pro. What was the code you were getting exactly? Is it possible you were reading the code wrong?

4runnerNB · 11-15-2009, 01:53 PM

I believe I read the code correctly. I've got an engine coming from a toyota mechanic who says the head is new, gaskets etc. Hopefully he's being honest about the engine. I'll probably rebuild my old engine just to get the experience and keep my 4runner going for years to come.

Murakami · 11-15-2009, 02:05 PM

pull the valve cover off and have a look and make sure your valves are all in spec.

thook · 11-15-2009, 02:15 PM

Quote:

Originally Posted by 4runnerNB

I believe I read the code correctly. I've got an engine coming from a toyota mechanic who says the head is new, gaskets etc. Hopefully he's being honest about the engine. I'll probably rebuild my old engine just to get the experience and keep my 4runner going for years to come.

Oh....that was a rather quick decision.

Good luck.

4runnerNB · 11-15-2009, 05:11 PM

So, if I find my valves aren't in check and I adjust them, is that going to get the engine running again on all 4.... what will that tell me if they're out of whack? I'd really like to find an easier solution than swapping out my engine, but I have to find it soon because my runner is my only vehicle on the road at the moment.

dannomite · 11-15-2009, 07:11 PM

You could have damage to your head gasket between the cylinders. Which would allow compression to leak into the next cylinder over. Just a thought.

abecedarian · 11-15-2009, 09:48 PM

1st- find a new mechanic to talk to.
2nd- nice to know you believe you read the code correctly. What was it again?
3rd- no... really... humor us and tell us what the code was...
4th- what were the readings on the compression test? ALL 4 CYLINDERS PLEASE.
5th- adjusting your valves isn't going to help if the cam is broken.
6th- Don't ask for help if all you'll do is waste our time.

JigsN Rigs · 11-16-2009, 12:48 AM

^ haha harsh reality.. I'm on 3vze I lost all compression on cylinder 1 and it was knocking real bad.. I'm in the process of dissassembly now

4runnerNB · 11-16-2009, 02:12 PM

I was getting a code 22, engine coolant temp sensor. I know how to properly check trouble codes, but engine internals are not exactly my area of specialty. I've had just about everything apart and back together on 4runners except engines and trannys. I figured someone might have had the same problem and might be able to tell me what they had to fix. I haven't done a compression test myself, I just might tonight when I go drop off my replacement engine. As far as doing a compression test and checking valves I can't think of anything else I can do to see what went wrong short of tearing the engine down, which I will do eventually so I can have a back up that I might juice up a little.

thook · 11-16-2009, 07:53 PM

Well, causes for compression loss would be busted rings, busted pistons, blown gasket, dead valves, cracked cylinders.......but, it's knocking.

Any smoke? What color, if any?

I'd pull the valve cover and drain the oil......maybe even drop the pan. See if there's any metal in the oil or even a copper tone to it.

JigsN Rigs · 11-17-2009, 12:40 AM

Yes but if his.rings are shot he would still be getting a little compression. When you have zero compression it could most likely be a busted rod, hole in ur piston, or a valve that is stuck open. I just got the heads off on my 3vze and found my issue was a busted rod. I'm guessing you might be in the same boat.. Good luck yoda

11-15-2009, 02:05 PM	#5 (permalink)
Murakami Registered User Join Date: Jul 2009 Location: NYC Posts: 43	pull the valve cover off and have a look and make sure your valves are all in spec. __________________ 93 Pickup, std. cab, 22re, 5 spd., 33x12.5 Mickey Thompsons on 15x10 AR Outlaws and 4.88s.

11-15-2009, 07:11 PM	#8 (permalink)
dannomite Registered User Join Date: Aug 2008 Posts: 237	You could have damage to your head gasket between the cylinders. Which would allow compression to leak into the next cylinder over. Just a thought. __________________ 1996 SR5 5speed rear locker.

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11-15-2009, 07:56 AM	#2 (permalink)
peapicker Registered User Join Date: Apr 2009 Location: Morganton, NC Posts: 178	my 2 cents. Im a fan of rebuilding what you have. When done you know exactly what is in your engine and what kind of shape the internals are in. when a used engine is bought, its just a guessing game as to how dependable it is.

11-15-2009, 01:53 PM	#4 (permalink)
4runnerNB Registered User Join Date: Feb 2009 Posts: 10	I believe I read the code correctly. I've got an engine coming from a toyota mechanic who says the head is new, gaskets etc. Hopefully he's being honest about the engine. I'll probably rebuild my old engine just to get the experience and keep my 4runner going for years to come.

11-15-2009, 05:11 PM	#7 (permalink)
4runnerNB Registered User Join Date: Feb 2009 Posts: 10	So, if I find my valves aren't in check and I adjust them, is that going to get the engine running again on all 4.... what will that tell me if they're out of whack? I'd really like to find an easier solution than swapping out my engine, but I have to find it soon because my runner is my only vehicle on the road at the moment.

11-16-2009, 12:48 AM	#10 (permalink)
JigsN Rigs Registered User Join Date: Nov 2009 Location: Hudson, WI Posts: 35	^ haha harsh reality.. I'm on 3vze I lost all compression on cylinder 1 and it was knocking real bad.. I'm in the process of dissassembly now

11-16-2009, 02:12 PM	#11 (permalink)
4runnerNB Registered User Join Date: Feb 2009 Posts: 10	I was getting a code 22, engine coolant temp sensor. I know how to properly check trouble codes, but engine internals are not exactly my area of specialty. I've had just about everything apart and back together on 4runners except engines and trannys. I figured someone might have had the same problem and might be able to tell me what they had to fix. I haven't done a compression test myself, I just might tonight when I go drop off my replacement engine. As far as doing a compression test and checking valves I can't think of anything else I can do to see what went wrong short of tearing the engine down, which I will do eventually so I can have a back up that I might juice up a little.

11-17-2009, 12:40 AM	#13 (permalink)
JigsN Rigs Registered User Join Date: Nov 2009 Location: Hudson, WI Posts: 35	Yes but if his.rings are shot he would still be getting a little compression. When you have zero compression it could most likely be a busted rod, hole in ur piston, or a valve that is stuck open. I just got the heads off on my 3vze and found my issue was a busted rod. I'm guessing you might be in the same boat.. Good luck yoda