Head Gasket/Head vs Rebuilt Motor

[Langcow1]

Related question -

My 4runner started running rough. Mechanic1 thinks it’s the #6 injector but I replaced all injectors with a set from Motorwest 15,000 miles ago.

Mechanic2 did a compression test on cyl6 and got 175 psi and then a leakdown test and found a 15% leak. He thinks it’s a valve.

Today I took it to Firestone for lifetime alignment and had them run compression test on all cylinders. Here are the results:

1: 190
3: 180
5: 125

2: 90
4: 170
6: 190

Anybody have any suggestions? Could they both be right… like the injector could have failed and that’s what’s causing the currently rough idle but the compression is also a secondary, and larger, issue? Or is the compression obviously causing the rough idle?

Anybody ever try that Engine Restore additive? Some youtube reviews sound promising, for a quick temporary fix anyway.

 

[Langcow1]

(Sorry to hijack your thread Slothy! I too am likely looking for a reman from someplace that can get it quicker than Yota1)

 

[brillo_76]

Related question -

My 4runner started running rough. Mechanic1 thinks it’s the #6 injector but I replaced all injectors with a set from Motorwest 15,000 miles ago.

Mechanic2 did a compression test on cyl6 and got 175 psi and then a leakdown test and found a 15% leak. He thinks it’s a valve.

Today I took it to Firestone for lifetime alignment and had them run compression test on all cylinders. Here are the results:

1: 190
3: 180
5: 125

2: 90
4: 170
6: 190

Anybody have any suggestions? Could they both be right… like the injector could have failed and that’s what’s causing the currently rough idle but the compression is also a secondary, and larger, issue? Or is the compression obviously causing the rough idle?

Anybody ever try that Engine Restore additive? Some youtube reviews sound promising, for a quick temporary fix anyway.

How many miles on your engine? If 250 to 300k. Do a antifreeze leak down test. If the coolant pressure staying. You may need valves adjusted. That one cylinder is really bad.

And bubbles on your antifreeze? That cylinder may have a head gasket issue as well.

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[Bad Luck]

Related question -

My 4runner started running rough. Mechanic1 thinks it’s the #6 injector but I replaced all injectors with a set from Motorwest 15,000 miles ago.

Mechanic2 did a compression test on cyl6 and got 175 psi and then a leakdown test and found a 15% leak. He thinks it’s a valve.

Today I took it to Firestone for lifetime alignment and had them run compression test on all cylinders. Here are the results:

1: 190
3: 180
5: 125

2: 90
4: 170
6: 190

Anybody have any suggestions? Could they both be right… like the injector could have failed and that’s what’s causing the currently rough idle but the compression is also a secondary, and larger, issue? Or is the compression obviously causing the rough idle?

Anybody ever try that Engine Restore additive? Some youtube reviews sound promising, for a quick temporary fix anyway.

Sounds like mechanic #1 is throwing a parts dart and doesn't know. Either Mechanics #1&2 are wrong about it being cylinder #6 or the compression readings are incorrect. The compression readings indicate a problem with #2 and #5, but the first 2 mechanics claim it's cylinder #6.

I would recommend trying a different mechanic to do the compression testing and then leak down testing the problem cylinder(s). A leak down test will tell them if it's head gasket, piston rings, or valves/seals.

 

[brillo_76]

It's most likely the low compression causing the rough idle.

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[Langcow1]

Man, I said it before and I'll say it again. There are great people on this forum with a wealth of knowledge and advice.

It's a good thing to have help. We need more of that these days.

God Bless you guys!

Seconded! Bad Luck has given me good advice on more than one occasion, and thank you to Brillo too. I’m out of town at the moment but will be acting on their advice in the coming week.

 

[Langcow1]

Is there any reason to leak down test the cylinders with good compression? Like any that test above 170?

 

[Bad Luck]

Is there any reason to leak down test the cylinders with good compression? Like any that test above 170?

Nope. Leak down test is to determine why a cylinder has low compression. If a cylinder has hood compression then a leak down test won’t find any issues. Generally speaking 10% leak down is the acceptable threshold.

 

[Langcow1]

Ok cool - thanks man

 

[Langcow1]

Ok, re-doing my compression test was good advice. I added a can of Engine Restore and drove it about 120 miles. Got a compression tester from AutoZone and did the test with the engine really warmed up from driving around. Here’s the results (much better than Firestone’s #s posted above):

1: 195
3: 200
5: 200

2: 192
4: 200
6: 195

Engine is still running rough, especially on the highway. Still no check engine light on. What I noticed is that the fresh air intake hose is cracked pretty badly where it connects to the throttle. So I have one of those on order and I’ll see how it runs after that.

 

[Langcow1]

Unless there’s another crack somewhere, it’s not the air intake hose because I wrapped it up with electrical tape and clamped it on tight and I still have the same problem. Maybe it really is the fuel injector. I’d be more convinced if the check engine light was on.

 

[Bad Luck]

Unless there’s another crack somewhere, it’s not the air intake hose because I wrapped it up with electrical tape and clamped it on tight and I still have the same problem. Maybe it really is the fuel injector. I’d be more convinced if the check engine light was on.

I chased a misfire on my last 4Runner. It never set a code besides P0300. I convinced myself it was injectors, but was wrong on that parts dart. Have you checked the resistance of the coil pack primary and secondary sides?

 

[brillo_76]

Compression looks fairly even now so that let's us know that the piston rings and valves are working good without bad head gaskets.

So this leaves spark and fuel.

What do the plugs look like? When I had an injector fail it threw a misfire code on cylinder 5. We swapped the plug and coil to cylinder 1. Then checked cylinder 5 spark plug . Bone dry. Thus proving the injector was bad.

It's possible the wires are done if you haven't changed the plugs and wires out, probably wouldn't be a bad idea. I have a link on my signature that gives you the specs wiring diagram and what the coils values should be.

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[Langcow1]

Could the cracked air intake have caused something to fail prematurely? The weird part of this is that I did plugs, wires, coils, O2 sensors, and Motorwest injectors a year and a half ago (14,000 miles). So one of those could have failed but it would be an early failure.

I’m no expert but there was nothing obviously odd looking about any of the spark plugs when I had them out.

 

[brillo_76]

Could the cracked air intake have caused something to fail prematurely? The weird part of this is that I did plugs, wires, coils, O2 sensors, and Motorwest injectors a year and a half ago (14,000 miles). So one of those could have failed but it would be an early failure.

I’m no expert but there was nothing obviously odd looking about any of the spark plugs when I had them out.

I cracked air intake would cause the engine to run lean as its getting too much air. That be it..

 

[19963.4lsr5]

I cracked air intake would cause the engine to run lean as its getting too much air. That be it..

By the air bypassing the MAP sensor.


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[brillo_76]

By the air bypassing the MAP sensor.


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Correct. Thanks for the add on. As it getting more air then it should causing a lean conditon..

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[Langcow1]

New hose gets here Fri hopefully, and I have my old ignition coils so I can try swapping with those and see if that makes a difference. I’m also going to try changing the fuel filter. I’m not sure if it has ever been done.

 

[Langcow1]

Well I’ve been going about this bassackwards. My friend suggested that misfiring without the CEL on likely means that the CEL isn’t working. Sure enough, code reader gave me a cylinder 6 misfire. Swapped the ignition coils between 3 & 5, cleared codes, checked again and it’s still a cylinder 6 misfire. I guess it could be the wire or plug but in a roundabout way I am likely back to the #6 injector like the original mechanic said.

(Plugs, wires, coils were all changed with new Densos 14,000 miles ago, and the injectors were changed at the same time with a set from Motorwest, and I do have another set from Motorwest that they sent me a couple of weeks ago under warranty)

 

[Bad Luck]

Well I’ve been going about this bassackwards. My friend suggested that misfiring without the CEL on likely means that the CEL isn’t working. Sure enough, code reader gave me a cylinder 6 misfire. Swapped the ignition coils between 3 & 5, cleared codes, checked again and it’s still a cylinder 6 misfire. I guess it could be the wire or plug but in a roundabout way I am likely back to the #6 injector like the original mechanic said.

(Plugs, wires, coils were all changed with new Densos 14,000 miles ago, and the injectors were changed at the same time with a set from Motorwest, and I do have another set from Motorwest that they sent me a couple of weeks ago under warranty)

I’d swap the spark plugs and resistance check the wires before going through the effort of changing injectors again. Injectors are not a common failure point.