Sooty Exhaust

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
lesk
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Sooty Exhaust

Post by lesk » Tue Aug 29, 2017 7:19 pm

New to this forum...I have a 67 CDN2...runs well and smooth but it really soot's up the exhaust pipe....I have tried to lean out the mixture buy turning the mixture screw counter clockwise but I am not sure what to look or listen for.

Thanks in advance,

lk


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Re: Sooty Exhaust

Post by Scoutpilot » Wed Aug 30, 2017 2:26 am

The idle mixture screw needs to be at 1 1/4 to 1 1/2 turns out from lightly seated. Turning it more counter-clockwise enriches the mixture.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
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Re: Sooty Exhaust

Post by lesk » Wed Aug 30, 2017 7:26 pm

Thanks Scoutpilot....I will turn the screw clockwise now to lean out the mixture this time.
I have other issues with this newly to me 67' M38A1-CDN2....if you care to tackle them...originally, my temp gauge always read about 140 F... did not matter of outside temp but averaged 75F, hilly-flat whatever....plus, the temp gauge always fogged up and the rad puked coolant from the overflow and coolant dribbled from the 3 pulley water pump.....so, I pulled and flushed the rad of all its sludge, replaced the water pump and went to replace the thermostat but there was none.....so I put one in.....now, with a 160 F thermostat in place, flushed rad, new coolant and water pump the temp gauge rarely fogs up, the rad does not puke coolant but the temp gauge now always goes to 182 F but no more.....why so high when all was cleaned or replaced?...I though that 160 F was normal?....can it be a dubious gauge or sender & which one?

The jeeps rear spring packs are 12 springs on the driver side and 13 (added leaf) on the passenger side.....it carried over 200 lbs of radio gear on the passenger side....so, I get a vibration between 25 & 35 MPH....after that all is smooth all the way to 45-50 MPH....why the vibration....can it be due to over angulation of the "U" joint at the transfer case....which does appears somewhat over angular-IE...not straight?

Also, what engine oil is appropriate....I have read that diesel 15W40 is best (due to zinc content)....lesser volume of people say it does not matter as any oil today is better that yesterdays oil....the engine rebuilder (retired Canadian Forces mechanic....worked on jeeps all his 25 year career) says that I should only use 15W40...your opinion would be most valued.

Thanks.....lk

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Re: Sooty Exhaust

Post by Scoutpilot » Thu Aug 31, 2017 1:25 am

My expertise is carbs and pumps, but I’ll try.

1. What is the psi rating on the radiator cap? Did you drill a 1/8” hole in the skirt of the thermostat? Straight water or 50/50 antifreeze/water? 170-180 is normal in hilly country driving, as long as it returns to a cooler temp at some point.

2. Where do you feel the vibration? Steering wheel or seat? Check your tire air pressure. Make sure the wheels are balanced. One of the wheels may have thrown a weight. Be sure the spring packs are tight.

3. Your mechanic is correct. Rotella 15W40 is excellent. Don’t buy a synthetic! Your friends who say “any” oil is better are not appreciating the metallurgy and tolerances in newer design motors as opposed to our older designs.

I hope this helps.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
'69 CJ5

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Re: Sooty Exhaust

Post by Jeeps4Brains » Thu Aug 31, 2017 4:11 am

My M38A1 has a rebuilt carb and runs great but still has a sooty exhaust. It does not smoke but over time the end of the pipe gets sooty. I am getting almost 14 mpg. For some reason this carb just runs a little rich. Normal MPG is around 15. Alan
45' MB, ??' MBT, 47' CJ2A, 48' CJ2A,
51' M38 #1, 51' M38 #2, 51' M100,
52' M37, ??' M101A1 (1st Gulf War Vet),
53' M38A1, 53' M211, 65' M151A1, 67' M416,
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Re: Sooty Exhaust

Post by lesk » Thu Aug 31, 2017 5:27 pm

Hi ScoutPilot & Alan...thanks for your reply's.....I will respond to Alan first...not sure if carb is rebuilt or not but the jeeps starts very quickly, idles nicely and does not smoke at any time.....just sooty exhaust.

OK...ScoutPilot...

1. The PSI rating on the cap is 4 lbs....as per the Canadian M38A1-CDN manual. No, I did not drill a 1/8 inch hole in the skirt in the thermostat (not sure why?) and the coolant is about 60/40 (coolant/prestone to water) as per the manual...and no it does not return to a cooler temp....after 10 min of driving its always at 180 F. Should I take off the thermostat as it was earlier?....it always ran cooler at about 130-140 F without the thermostat.

2. Vibration is felt all around...25 to 30 MPH....somewhat corresponds to rattling noise of hand brake. Tire pressure is 25 PSI all around....I tightened the spring packs a few days ago...but have not balanced the wheels.
Maybe the shift times/RPM are wrong....I normally on a flat surface shift from 2-3 at about 25-30 MPH....maybe I'm lugging the engine and causing vibration? What do you shift at?

Your response would be very helpful,...so would yours Alan.

Regards,

lk

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Re: Sooty Exhaust

Post by Scoutpilot » Fri Sep 01, 2017 1:06 am

Once the page is printed it is forever. Unfortunately chemical formulas do change for various reasons. Vehicles get older and wear changes them. The coolant of ’17 is not the same as the coolant of ’67. For those reasons, try a seven-pound radiator cap and use a 50/50 mix. Continue with the 160º thermostat, but drill an 1/8” hole anywhere in the skirt so long as coolant and, more importantly, air, can freely pass through. The hole allows the motor to “burp” itself of air. Air pockets in the cooling jacket are heat magnets and can lead to premature failure.
Balance your wheels. Double check your timing because too far advanced timing will cause higher operating temps, as will too lean a mixture.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
'69 CJ5

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Re: Sooty Exhaust

Post by lesk » Fri Sep 01, 2017 7:52 pm

Thanks ScoutPilot.........I will replace the coolant as well as install a 7 lb rad cap.....not sure about the hole in the thermostat....the small tube leading from the water pump to the cylinder head....is this not a coolant & air passage way?

Regards,

lk

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Re: Sooty Exhaust

Post by Scoutpilot » Sat Sep 02, 2017 1:07 am

You are correct. However, the thermostat is the highest point on the motor side of the cooling system. Not drilling the hole means trapped air that must be removed somehow.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
'69 CJ5

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Re: Sooty Exhaust

Post by lesk » Sun Sep 03, 2017 5:35 am

Thanks ScoutPilot...I will first look at the thermostat installed.....when I installed it I did not look at the back to verify if it was in fact a 160 F thermostat....I assumed it was as that is what I ordered....that being said, is it better to run the jeep at a constant 140 F (without a thermostat) or at 180 F (with a supposedly 160 F thermostat)? What would be your preference and why?

lk

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Re: Sooty Exhaust

Post by Scoutpilot » Sun Sep 03, 2017 10:02 am

The thermostat is designed to regulate the temperature of the coolant and thereby the temperature of the engine. Do not assume that a correctly operating thermostat will allow higher temperatures. No thermostat means no temperature control and can be worse than a nonfunctioning thermostat. The engine was designed with a thermostat. Why screw with a working design? Proper maintenance of the cooling system and careful attention to proper tuning specifications will yield normal operating temps for the climate you are in and the normal operational parameters you encounter.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
'69 CJ5

lesk
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Re: Sooty Exhaust & spark plugs

Post by lesk » Sun Sep 03, 2017 10:55 am

Thanks for your reply ScoutPilot....I am just concerned about the contact 180 F engine temps when they should be about 160 F (from the internet).

Another issue if you car to tackle it.... I am now confused about which spark plugs to use....I finally pulled the plugs from my M38A1-CDN2...the first plug closest to the rad was an Autolite 2245...the rest of them were Autolite 2243.....all 4 came out well and all 4 had a light tan colored resistor/ceramic (is this good?).

OK...so which spark plug (Autolite 2243 or 2245)is correct for this application (F head) as I am confused. An on line jeep store sent me Autolite 2243's a month ago before I realized that there may be other more appropriate applications.

Thanks for your response.

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Re: Sooty Exhaust

Post by Scoutpilot » Sun Sep 03, 2017 11:59 am

Read this, http://www.stant.com/index.php/english/ ... ermostats/ I’ll probably get an argument, but I’d run the 2245.
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
'69 CJ5

lesk
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Re: Sooty Exhaust

Post by lesk » Sun Sep 03, 2017 7:56 pm

Wow.....very informative link....thanks...I have copied it and will put it into my archives for future reference. OK....so you suggest going to 2245's....which leads me to many other questions....only if you have the time to answer.

1. Again, what is the optimal constant temp that the jeep should run at during the summer months in Canada?

2. Why do I show a constant 180 F with a 160 F thermostat installed and will 180 F slowly destroy the engine & head gasket?

3. Again, as I took out the old plugs, the first was a 2245 and the 3 others were 2243's.....all 4 showed a light beige/tan colored insulator.....is this normal?

4. If a 2245 is a hotter plug than a 2243...how come they both had the same light tan insulator suggesting even burning?

5. I loose about 1/2 quart of 15W40 in about 200 miles...the plugs are a nice tan color suggesting no oil burning, the jeep on start does not blow blue smoke suggesting that the valve seals are fine and the jeep does not smoke while driving even uphill struggling, there is no oil droplets visible in the clean, bright green prestone coolant and finally the only visible oil leak is 1-2 drops per day coming from the rear main seal area.....where is the oil going?

Stumped!

Regards,
lk

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Re: Sooty Exhaust

Post by Scoutpilot » Mon Sep 04, 2017 1:51 am

lesk wrote:
Sun Sep 03, 2017 7:56 pm
Wow.....very informative link....thanks...I have copied it and will put it into my archives for future reference. OK....so you suggest going to 2245's....which leads me to many other questions....only if you have the time to answer.

1. Again, what is the optimal constant temp that the jeep should run at during the summer months in Canada?

It’s all going to depend on the condition of the engine overall, the weather, the terrain and the traffic. As the article explained, with a 160º thermostat you should expect operating temps between 160 and 185.

2. Why do I show a constant 180 F with a 160 F thermostat installed and will 180 F slowly destroy the engine & head gasket?

You only need to worry when the temperature hovers around 210º and stays there. Oil begins to break down and friction within the motor increases.

3. Again, as I took out the old plugs, the first was a 2245 and the 3 others were 2243’s.....all 4 showed a light beige/tan colored insulator.....is this normal?

A correct fuel/air ratio will yield this result.

4. If a 2245 is a hotter plug than a 2243...how come they both had the same light tan insulator suggesting even burning?

How old are these plugs? Only guessing here but perhaps the 2245 is much older, and therefore less efficient than the cooler 2243s.

5. I loose about 1/2 quart of 15W40 in about 200 miles…the plugs are a nice tan color suggesting no oil burning, the jeep on start does not blow blue smoke suggesting that the valve seals are fine and the jeep does not smoke while driving even uphill struggling, there is no oil droplets visible in the clean, bright green prestone coolant and finally the only visible oil leak is 1-2 drops per day coming from the rear main seal area.....where is the oil going?

Oil leaks are the result of poorly matching machined surfaces coupled with old gaskets and seals. Most often an aggravating factor is poor maintenance on the PCV system leading to excessive pressures in the crankcase, leading to seal/gasket leakage.
Stumped!


Regards,
lk
'70-'71 'A' Batt., 377th FA, 101AB
(Slicks and LOH's)(Col's LOH Pilot)
'71-72 CHARLIE TROOP,
16TH AIR CAV, 1ST AVN BDE (AEROSCOUTS)
LOW LEVEL HELL.
'46 CJ2A
'47 CJ2A
'48 CJ2A
'48 B1PW126
'69 CJ5


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