Wife wants me to inch forward..... smell is too strong.

[MrLiken]

Hi all,

 

Well, I finally got her running again, and thought she was going pretty good.  My boss makes me drive with the wind screen open (when she rides up front), because of the exhaust smell.  Yesterday, we took some friends out for a ride.  If I stop at a light, she tells me to move up so they don't smell the fumes!  I'm stopped at a light - I can't move up!

I started reading here to try and get some ideas.  I read one post that suggested the "screwdriver to spark plug test".  I did that, and found a noticeable decline in idle in all cylinders Except #1.  There is no difference there.  I removed the piston covers and see that the pistons are not frozen.  I also checked compression using my finger and it does appear to have good compression.  I will verify tomorrow after I get my compression gauge.  The #1 spark plug was dry and very black.  I assume that it is running quite rich.  Is that what she is smelling?  I also tightened down the exhaust manifold bolts, in case I had a manifold leak from the head.  

Your expertise is much appreciated.

John 

[Bloo]

If you do have a cylinder not firing that will stink to high heaven.

 

If that is the case, 1/6 of the fuel/air mixture that the car uses is getting dumped in the exhaust. Some of that will burn in the exhaust but a lot will not. Rich or lean doesn't really matter when you have that going on, other than to help troubleshoot the cause. Either way, rich or lean, If you had an exhaust analyzer it would be pegged on the HC scale. HC represents raw gas more or less.

 

The compression test is a good place to start. Let us know how that goes.

 

[nearchoclatetown]

If he's talking about the '15 DB it would be 1/4. Are you sure there is spark to the plug? Hold the wire about 1/2 inch from the plug while it is running and make sure spark is jumping to the plug. That intensifies the spark, might make it sound different. Another issue MAY be your wife is used to smelling exhaust from a new car with a catalytic converter which basically has no smell. Any pre-cat car will have a strong odor. 

[Minibago]

This could be a lead.

A plug.

A burnt exhaust valve.

An exhaust too short and exiting under the car.

But…… it could also be blow by from the rings causing crankcase compression and blowing fumes out of the oil filler.
Remove the plug from number one

connect it to the lead and lay it down on the head

if you have spark at the plug then it is not spark.

carry out a compression test with a proper compression tester to ensure equal compression on each cylinder (should be around 55psi each)

check exhaust pipe exit point.

Undo the oil filler lid and with the engine running place a plastic or paper bag over the oil filler to see if it inflates.

[MrLiken]

2 hours ago, nearchoclatetown said:

If he's talking about the '15 DB it would be 1/4. Are you sure there is spark to the plug? Hold the wire about 1/2 inch from the plug while it is running and make sure spark is jumping to the plug. That intensifies the spark, might make it sound different. Another issue MAY be your wife is used to smelling exhaust from a new car with a catalytic converter which basically has no smell. Any pre-cat car will have a strong odor. 

I am talking about the 15.  It does have good spark.  Just no discernible difference when I ground it out. 

[Minibago]

Compression test then please.

I think you are looking at a burnt exhaust valve.

Or………an experience I had was with an original two part valve, the head welded to the stem parted company.

 

[MrLiken]

My compression test results: (psi)

1 - 14

2 - 25

3 - 40

4 - 35

Edited August 25, 2023 by MrLiken
clarification of units (see edit history)

[Bloo]

What units are those? Is that PSI?

 

[MrLiken]

Yes, psi

[Minibago]

Compression test indicates several burnt valves.

You will need to remove the head and all will be revealed.

A set of valves, a “decoke” and valve seat regrind will be a start.

 

A squirt or two of oil down each cylinder and a retest of compression will show a rise if rings are worn but valves are good.

[MrLiken]

These are from early June, when I replaced the head gasket and set my timing.

[Bloo]

I see a burned valve on that end cylinder (#1?). That tracks with "14" and the fact that you got no change when you shorted out the #1 plug. #4 looks like a mess too. I agree with Minibago. Take it apart and grind the valves. Some of them will be too far gone to grind and will have to be replaced.

[nearchoclatetown]

Replace them all. And don't just lap the new ones in, cut the seats. Do it right.

[MrLiken]

Thank you all.  On to looking for a shop to do the work.  The engine was rebuilt, 20 something years ago and apparently has about 100 very rough miles on it. 

I appreciate all of the advice!!

[Bloo]

Once repaired, be sure to double check valve tappet clearance before you run it. If valves burned in 100 miles, there is a high probability they were set too tight.

 

 

Edited August 25, 2023 by Bloo (see edit history)

[nearchoclatetown]

I'm a sceptic, but I doubt you can burn valves that bad in 100 miles. They MAY have lapped them but they did not do a real valve job. I agree on checking adjustment when finished. I personally do not like seats to be ground. I bought a New-Way cutter, it cuts with carbide and does a wonderful job. Expensive but worth every penny. 

[MrLiken]

Thank you Bloo and Doug!  Taking it by a shop in an hour.  Keep you updated.

Have a great weekend.

John

[nat]

     The deposits show oil consumption on all four cylinders.  #4 has a big bad head gasket leak next to/aft of the exhaust valve.  #s 3,2 and 1 show some leakage near the studs between the valves.

     Seat the valves if the valves and/or seats are pitted and and not shiny all the way around.

     55 Ft./Lbs torque on the head nuts.  Retorque after it's been hot and within 250 miles after that.

[MrLiken]

250 miles?  That will take me another 20 years! 

Thanks.  It is now in the shop getting torn down.  Can't wait to see what else they find...

[Bloo]

54 minutes ago, MrLiken said:

250 miles?  That will take me another 20 years! 

Maybe not, once it runs right. Good luck with it!

 

 

[MrLiken]

In one shop and back out after 3 weeks.  Took them that long to take the head off.  They were in, over their heads. 

I got it in to a mechanic that worked on her in the past.  Actually, he came out to the house with his equipment to grind and cut seats for the valves.  On closer exam, he found that there was way too much play in the valves and that the engine needed to be pulled.  He has it now and is getting new valves, guides, pistons and rings.  Said the bottom half looked pretty good.  Did some polishing of the shaft due to old burn marks from who knows how long ago. 

Will keep you updated.