Miss and backfire?

Tiny
VISHAL VISHAL
  • MEMBER
  • 1991 FORD SIERRA
  • 3.0L
  • V6
  • 2WD
  • MANUAL
  • 37,518 MILES
Just replaced the head gaskets as it was damaged by no 3 pistons. It started fine but now has a miss and backfire when I start. After 10 minutes of the engine running and warming up it comes right. But if I switch it off for an hour the same thing happens.
Monday, September 12th, 2022 AT 7:04 AM

3 Replies

Tiny
BORIS K
  • MECHANIC
  • 799 POSTS
Hello,

It sounds like the engine might have a possible issue with valve clearances, possibly tight.

The engine is a 3.0 V6 Essex

A good video:
https://youtu.be/1TKavblvTAg

Valve Clearances - Adjust
To check valve clearances, turn the crankshaft until the valves in the first column are fully open, when the valves shown in the second column may be checked and adjusted as required:
Valves Open Valves to Adjust
1 and 6 10 Ex and 7 In
8 and 11 5 Ex and 4 In
2 and 3 9 In and 12 Ex
7 and 10 6 In and 1 Ex
4 and 5 11 In and 8 Ex
9 and 12 2 In and 3 Ex
To adjust the valve clearance, turn the rocker arm retaining nut in either a clockwise or anti-clockwise direction until the correct clearance has been obtained. Rock the arm to ensure correct seating and recheck the clearance.
Valve clearances are:
V6 Inlet 0.013 in. (0.33 mm.), Exhaust 0.022 in. (0.55 mm.) for Hot engines.

Hope this helps.

Cheers, Boris
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Monday, September 12th, 2022 AT 8:05 AM
Tiny
VISHAL VISHAL
  • MEMBER
  • 1 POST
Hi. Thank you. Yes, tappets were too tight, but I also checked the carburetor and found that the power valve diaphragm was torn. It's a 38 Webber carburetor. Could this have added to the problem?
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Friday, September 16th, 2022 AT 9:46 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Vishal Vishal,

I noticed you haven't been contacted for a few days. Have you made any progress? Also, the power valve can cause a hesitation. I don't feel it would cause a backfire.

Let me know.

Joe
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Monday, September 19th, 2022 AT 6:16 PM

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