Engine cranks, will not start

Tiny
CYNTHIA HAYNES
  • MEMBER
  • 1998 TOYOTA 4RUNNER
  • 2.7L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 271 MILES
Had to replace with a new head. Engine had gotten hot an cracked old head. Temp gauge was not working at the time. New head, 2 cams, spark plugs an wires new, an getting spark. Fuel all seems ok. Fuses checked an seem good. Cranking will not start. Do not have air flow connected when trying to crank. Getting compression of 115 or 125 on all 4 cylinders
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Wednesday, June 8th, 2022 AT 10:48 AM

8 Replies

Tiny
AL514
  • EXPERT
Hello, you don't have the mass air flow sensor and the air intake tube on? You'll need that to be plugged in and the air intake tube sealed up correctly. The mass air flow sensor also includes the Intake air temperature sensor.

https://www.2carpros.com/articles/how-a-mass-air-flow-sensor-works-maf
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Wednesday, June 8th, 2022 AT 12:21 PM
Tiny
CYNTHIA HAYNES
  • MEMBER
I was mistaken the air flow sensor was still hooked up, did hook the tube back up. Still not cranking. Possibly the cam positioning sensor believe possibly bad from when engine got so hot, not sure. Going to take radiator, etc, apart early am. Possibly the timing jumped, seemed perfect when put back together. Did try to fire up 2 times initially. What is your experience with these two things? Thank you
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Wednesday, June 8th, 2022 AT 3:08 PM
Tiny
CYNTHIA HAYNES
  • MEMBER
Guessing there is no way to check the positioning sensor before having to remove timing gear.
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Wednesday, June 8th, 2022 AT 3:09 PM
Tiny
CYNTHIA HAYNES
  • MEMBER
Did get the info on checking the sensor answered.
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Wednesday, June 8th, 2022 AT 3:19 PM
Tiny
AL514
  • EXPERT
If you just replaced the cylinder head, and I'm assuming you got a new head with new valves and the whole assembly. 2 new cams, did you replace the timing chain and chain tensioner? The minimum compression for a used engine is 127psi, Compression with a new head and components should be up around 178psi. 115 is definitely too low and 125 sounds too low too for a new cylinder head.
The diagrams on All Data look different than what I would expect. This is a dual overhead cam, correct? And does it have a 2-chain setup? The 1st diagram below is supposed to be the 2.7liter and so is the 2nd diagram, but it only shows 1 cam on the 2nd. I think this service information is wrong. But if you have low compression like that, I'd say the timing chain might be off by 1 or 2 teeth on either cam, or the crankshaft. But they don't give any information as to where the timing marks are. Same information on All Data and Mitchell. But if you reused the old chain, and/or tensioner, that might be where things went wrong. The low compression is the clue to what's going on.
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Wednesday, June 8th, 2022 AT 7:04 PM
Tiny
CYNTHIA HAYNES
  • MEMBER
Going to replace the timing chain and gear. Thank you for the help.
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Thursday, June 9th, 2022 AT 9:11 AM
Tiny
AL514
  • EXPERT
Try lining up the cams and see how far the chain jumped. If you find that the chain tensioner is extended all the way out, or the timing chain guards have worn a groove in them from the chain, that can cause it to be loose too. It might not be anything to do with the cam or crankshaft gear. It's the components that deal with keeping the chain tight.
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Thursday, June 9th, 2022 AT 10:53 AM
Tiny
CYNTHIA HAYNES
  • MEMBER
Thanks, will do.
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Thursday, June 9th, 2022 AT 10:56 AM

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