Maybe an engine issue ?

[Matt Colie]

The vast majority of my engine experience with engines that are highly instrumented and closely monitored. If I had that level of instrumentation,
there would be very little room left in the coach for us.

On the Shawnee run, our fuel rate and lube oil consumption have both gone the wrong way. I am used to clocking 9.2 MPG and about 2k miles on a quart.

This run was 8.48 and a little over 1K/qt. This is new. There is oil on the bottom that might account for the lube oil loss.
I just inspected the plugs and they don't match very well. These are XR451X gapped at 0.047.
The last set didn't match that well either, but much better than this. I know I saved them and got them out to compare. Those were Bosch WR9FPZ
gapped at 0.040. Those bothered me because the center electrode can recede into the insulator and you would never know.

The plugs are not what I expected at all. The front pair (1&2) are so dark that they could be fouled, but it is not oil. Those should be the two
that are hottest. The rest of the odd side (3,5&7) were much darker than the even side (4,6&8). 8 almost looks too hot. I really am hoping that
this is not telling me something I don't want to hear.

There is no running trouble at all and she is as smooth as ever.
Tomorrow I am going to rearrange the plugs and put the darkest were the lightest were and vice-versa.

Matt


--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[a.]

> The vast majority of my engine experience with engines that are highly instrumented and closely monitored. If I had that level of
> instrumentation, there would be very little room left in the coach for us.
>
> On the Shawnee run, our fuel rate and lube oil consumption have both gone the wrong way. I am used to clocking 9.2 MPG and about 2k miles on a
> quart.
> This run was 8.48 and a little over 1K/qt. This is new. There is oil on the bottom that might account for the lube oil loss.
> I just inspected the plugs and they don't match very well. These are XR451X gapped at 0.047.
> The last set didn't match that well either, but much better than this. I know I saved them and got them out to compare. Those were Bosch WR9FPZ
> gapped at 0.040. Those bothered me because the center electrode can recede into the insulator and you would never know.
>
> The plugs are not what I expected at all. The front pair (1&2) are so dark that they could be fouled, but it is not oil. Those should be the two
> that are hottest. The rest of the odd side (3,5&7) were much darker than the even side (4,6&8). 8 almost looks too hot. I really am hoping that
> this is not telling me something I don't want to hear.
>
> There is no running trouble at all and she is as smooth as ever.
> Tomorrow I am going to rearrange the plugs and put the darkest were the lightest were and vice-versa.
>
> Matt
Are you saying you think the intake manifold has a crack in the plenum on one side that is pulling oil in, burning it, and fouling the plugs on that
side? Associated low vacuum also accounting for MPG decrease?
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"When I grow up I am going to be a curmudgeon."

 

[steve southworth]

Would your spark plug condition be associated with the running cold problem you had. When I had a thermostat fail open MPG went down the sewer. The
choke would not fully open. My electric choke is the type that uses a control module attached to the head.

I doubt that has any affect on the oil consumption however.
--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

 

[ree.eric]

I have my manifold on the shop table for Dick Paterson stainless steel block off plates and I see that the connection for the vacuum brakes is closest
to #8. Cylinders 2,3,5,8 are fed from the right side of the manifold and 1,4,6,7 feed from the left side, this is the bottom feed path, is this where
it is likely to crack?
--
Eric & Ree '74 ex-Sequoia + '75 Eleganza Alexandria, Ontario, Canada

 

[dennis sexton]

Matt

You may be worried about nothing. Most of us probably would not have noticed anything.

But here are a few thoughts.

1) my recent reading of spark plug color indication suggests that it is difficult at best. Plug color can change very quickly with only the minimal
idling. One suggestion was to shut off the engine at 2000 rpm and coast to a stop before checking plug color to get any accurate info.

2) spark plug quality has also been more questionable of late. Maybe the current set you have is not truly of the heat range advertised

3) if I couldn't just let it go and continue to watch - I would send a sample for oil analysis to ensure no major issue was looming

Dennis

> The vast majority of my engine experience with engines that are highly instrumented and closely monitored. If I had that level of
> instrumentation, there would be very little room left in the coach for us.
>
> On the Shawnee run, our fuel rate and lube oil consumption have both gone the wrong way. I am used to clocking 9.2 MPG and about 2k miles on a
> quart.
> This run was 8.48 and a little over 1K/qt. This is new. There is oil on the bottom that might account for the lube oil loss.
> I just inspected the plugs and they don't match very well. These are XR451X gapped at 0.047.
> The last set didn't match that well either, but much better than this. I know I saved them and got them out to compare. Those were Bosch WR9FPZ
> gapped at 0.040. Those bothered me because the center electrode can recede into the insulator and you would never know.
>
> The plugs are not what I expected at all. The front pair (1&2) are so dark that they could be fouled, but it is not oil. Those should be the two
> that are hottest. The rest of the odd side (3,5&7) were much darker than the even side (4,6&8). 8 almost looks too hot. I really am hoping that
> this is not telling me something I don't want to hear.
>
> There is no running trouble at all and she is as smooth as ever.
> Tomorrow I am going to rearrange the plugs and put the darkest were the lightest were and vice-versa.
>
> Matt

--
Dennis S
73 Painted Desert 230
Memphis TN Metro

 

[Ken H.]

Dennis,

Shame on you! Why would you say something like that about current spark
plug production? You must not have seen this report on Chinese high-tech
production:

http://www.curezone.org/forums/am.asp?i=1063782

Ken H.

> ​...
>
> 2) spark plug quality has also been more questionable of late. Maybe the
> current set you have is not truly of the heat range advertised
>
​...​

 

[john r. lebetski]

I too go back to the running below temp. Did you ever solve that? Was it a slighly bad stat? Could your vac or mech adv be sticking after winters
nap? A new stat put my 230k 4L jeep back on the normal 195 mark. Previous stat was opening, but I suspect not fully. Perhaps yours was " working" on
stove top but not properly throttling against pump flow.
--
John Lebetski
Woodstock, IL
77 Eleganza II