Blown head gasket or or intake gasket?

BRIGUY

MEMBER
2001 CHEVROLET BLAZER
4.3L
6 CYL
4WD
211,000 MILES

P0300 code.
Number 5 plug oil fouled.
Oil from exhaust.
Fuel smell from exhaust.
White smoke from exhaust at 1,500 RPMs and higher.
No evidence of oil and coolant mixing.
Changed cap, rotor, plugs and wires (before I saw oil from exhaust).
No oil pressure loss, no overheating.
Cranking longer than usual before starting for about a week. Normally it would start immediately then I turned the key.

10 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

I would start by checking the fuel pressure. That would explain the long crank and the code for the misfire.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

As far as the white smoke, you need to do a leak-down test to see if the head gasket is leaking.

https://www.2carpros.com/articles/head-gasket-blown-test

I would also do a compression test to be sure there is no internal issue.

https://www.2carpros.com/articles/how-to-test-engine-compression

Report back with the results.

Roy

1. Disconnect the negative battery cable.
2. Relieve the fuel system pressure. Refer to Fuel Pressure Relief Procedure.
3. Drain the fuel tank. Refer to Fuel Tank Draining Procedure (Pick Up) or Fuel Tank Draining Procedure (2-Door Utility) or Fuel Tank Draining Procedure (4-Door Utility).
4. Remove the fuel tank.
5. Remove the fuel sender assembly.
6. Note the position of the fuel strainer (2) on the fuel sender
7. Support the fuel sender assembly with one hand and grasp the strainer (2) with the other hand.
8. Pull the strainer off the fuel sender. Discard the strainer after inspection.
9. Inspect the strainer. Replace a contaminated strainer and clean the fuel tank.
10. Disconnect the fuel pump electrical connector (5).
11. Remove the fuel level sensor electrical connector retaining clip (6).
12. Disconnect the fuel level sensor electrical connector (7) from under the fuel sender cover.
13. Remove the fuel level sensor retaining clip (4).
14. Squeeze the locking tangs and remove the fuel level sensor (3).
15. Remove the fuel pressure sensor (1).

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Thursday, March 25th, 2021 AT 5:06 AM

BRIGUY

MEMBER
6 POSTS

Okay, here's the situation so far:

compression tested good, number 6 and 4 tested 110 and 135 respectively but the rest are above 160. The fuel pump test came out good.
I have spark at all six cylinders and I cleaned the EGR.
When I started the engine to do the fuel pressure test it was running much smoother. When I scanned the codes again it shows only number 5 is misfiring.
There is still blueish white smoke coming from exhaust but no sweet coolant smell or taste (I'm an old guy that's how we checked for coolant in the exhaust years ago) but it seems to be diminishing.
I'm going to be replacing the coil and distributor just because it probably needs it after 200,000.
Still no signs of oil and coolant mixing.

Thank you for your time.

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Thursday, March 25th, 2021 AT 5:08 PM

ASEMASTER6371

MECHANIC
52,797 POSTS

Your blue smoke could be from the cylinders with low compression.

https://www.2carpros.com/articles/the-reasons-for-low-compression

what was the fuel pressure? This is what you need.

Key On Engine Off .................... 60-66 psi

Roy

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Thursday, March 25th, 2021 AT 5:14 PM

BRIGUY

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6 POSTS

Engine off 62
Running 55
Snap 60-62
Under load 68

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Thursday, March 25th, 2021 AT 5:31 PM

BRIGUY

MEMBER
6 POSTS

When I do the engine off fuel pressure test it holds at 60 for about four or five seconds then drops to zero, is that a problem? Otherwise while the engine is running it remains constant.