Engine stalls while driving down highway

Tiny
TOM C REINERTSON
  • MEMBER
  • 2004 TOYOTA SEQUOIA
  • 4.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 197,000 MILES
Vehicle quits while driving 65 mph down highway. Fuel pressure good and fuel is getting to engine. All belts are intact and on engine correctly. Right 4 cylinders have no compression. Check with borescope no broken valves or piston damage or scrapes gouges etc, in all cylinders. Car won’t start or run no engine lights or warning lights on. I’m stumped could this be the crankshaft sensor? I can’t think of any thing else that would disrupt one half of the engine? Help
Thursday, November 21st, 2019 AT 4:19 PM

2 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,816 POSTS
If you have no compression, then you have to have a valve open at the wrong time. Even if you had a bad head gasket, bad piston rings, or worn cylinder walls, you would have some compression.

With that, you need to remove the timing belt covers. Once you have access to both cam shaft pulleys, first place the crankshaft pulley at TDC. See pic 1. Then confirm that the cam timing marks are aligned Pic 2. You may have to fully rotate the crankshaft a few times for them all to align, but they at some point must align.

In the last pic, I circled the cam gears.

Now for the bad news. If the timing has jumped, there is a good chance internal engine damage has occurred. The 4.7 is an interference engine which means there isn't enough clearance between the pistons and valves and they will hit if timing is off. If you determine that the belt has jumped, the next thing to do would be remove the affected cylinder head and check for damage.

Let me know what you find. If you determine you want to replace the timing belt, I will provide the directions as well as cylinder head removal.

Joe
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Thursday, November 21st, 2019 AT 6:03 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,324 POSTS
Crankshaft sensor cannot cause no compression. That is either a bad cam or timing jumped and now valves are open when they shouldn't be. To add to what Joe said, see if you can get a leak down tester. It allows you to put air into the cylinders one at a time with them at top dead center. The valves should be closed and the piston all the way up, then you lock it so the crank doesn't move and apply air pressure through the spark plug bore. Now you listen for where the air is coming out. You will normally hear some coming through the dipstick tube because air will get past the rings but it shouldn't be a lot. Now the valves should be closed at this point so if you hear air through the intake or exhaust that is where the problem is. Do all the cylinders that have no compression and see what you find.
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Friday, November 22nd, 2019 AT 1:04 AM

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