Steam from exhaust on cold start

[mikelikesbbq]

Hi all,
I have an 02 KJ project with the 3.7. I've gotten most of the gremlins fixed and swapped all of the neglected nasty fluids that were likely original with 159K on them. It runs decent but on every cold start, there is a bit of white smoke that comes out of the tailpipe until it warms up. It's not a huge amount, but too much to be condensation, and it does smell sweet.

I've done the HG test for exhaust gases in the coolant and that was negative and the oil is not contaminated with water. None of the plugs looked cleaner (or dirtier) than the rest so that also tells me the HG is ok. It also has not dropped the coolant level, so I am thinking it may have a bad intake manifold gasket that is just dripping a little overnight and that is what's burning off on startup. Has anyone else seen this as a common issue, or perhaps something else that might cause a bit of coolant to get vaporized in combustion?

My back is shot so I'm hoping to avoid tearing into anything unless I really have to. Exploratory teardowns aren't really feasible for me anymore.

Thanks in advance for any ideas.

 

[tommudd]

How cold are we talking ?
50 ?
30 ?
0 ?

 

[mikelikesbbq]

I live in FL so more like 70, 80, 90!

 

[Ksat]

With the engine cold, I would top off the coolant reservoir and pressurize each cylinder at TDC with a leak-down tester (90 psi or so) and wait a good 5 mins to see if the coolant level rises just to double check you don't have a head gasket issue. A block test may not catch exhaust gases in the coolant if the leak is very slight. This test is pretty definitive: if the level doesn't rise, you don't have a bad head gasket or crack somewhere in that area. If you don't have a leak down tester, a compression tester may work for the task.

I've never done an intake manifold gasket on the Lib, but I don't think it comes in any contact with nor is used to seal out any coolant.

You may also want to use a coolant pressure tester to see how long the coolant system can hold pressure.

 

[mikelikesbbq]

With the engine cold, I would top off the coolant reservoir and pressurize each cylinder at TDC with a leak-down tester (90 psi or so) and wait a good 5 mins to see if the coolant level rises just to double check you don't have a head gasket issue. A block test may not catch exhaust gases in the coolant if the leak is very slight. This test is pretty definitive: if the level doesn't rise, you don't have a bad head gasket or crack somewhere in that area. If you don't have a leak down tester, a compression tester may work for the task.

I've never done an intake manifold gasket on the Lib, but I don't think it comes in any contact with nor is used to seal out any coolant.

You may also want to use a coolant pressure tester to see how long the coolant system can hold pressure.

Thanks, I have a friend with a pressure tester and will give that a shot and see how it goes. I've only put maybe 500 miles on it and the coolant level hasn't dropped so was hoping it was something minor. It runs cool even in 90+ degree weather with the AC going. Fingers crossed!

 

[Johnny O]

Hi all,
I have an 02 KJ project with the 3.7. I've gotten most of the gremlins fixed and swapped all of the neglected nasty fluids that were likely original with 159K on them. It runs decent but on every cold start, there is a bit of white smoke that comes out of the tailpipe until it warms up. It's not a huge amount, but too much to be condensation, and it does smell sweet.

I've done the HG test for exhaust gases in the coolant and that was negative and the oil is not contaminated with water. None of the plugs looked cleaner (or dirtier) than the rest so that also tells me the HG is ok. It also has not dropped the coolant level, so I am thinking it may have a bad intake manifold gasket that is just dripping a little overnight and that is what's burning off on startup. Has anyone else seen this as a common issue, or perhaps something else that might cause a bit of coolant to get vaporized in combustion?

My back is shot so I'm hoping to avoid tearing into anything unless I really have to. Exploratory teardowns aren't really feasible for me anymore.

Thanks in advance for any ideas.

White that smells sweet means the glycols in the coolant burning off. What’s your oil currently looking like? Got some mocha lattes at the drain plug on the oil pan?

 

[mikelikesbbq]

White that smells sweet means the glycols in the coolant burning off. What’s your oil currently looking like? Got some mocha lattes at the drain plug on the oil pan?

Actually the oil still looks perfect and there's no sign of milkshake on the cap or dipstick. I've not had to add coolant or oil in the 500 or so mile I've driven it while working the bugs out, and it runs nice and cool. The coolant reservoir does look a bit grimy, could possibly be oil contamination but also could just be rust and old coolant. I planned to flush it and refresh the coolant but want to make sure it doesn't need major work first.

Some history on this KJ, I bought it cheap as "non-running" and the owner said it just stopped running. I had at the time another KJ with a locked engine and thought this one might be good for parts. I went to check it out and it started right up, but ran pretty crappy. The seller said it ran when it wanted to and made him late to work too many times, and made his sister miss a flight when it died, and it hadn't been starting for a while. I was able to drive it up on a trailer and get it home. It had codes for misfire, injector control, battery voltage and trans pressure. Fixed a badly distorted and corroded battery ground terminal and most of them went away except for the misfire, which ended up being a bad spark plug. I think the loose ground was causing it to die and not restart as I remember having my smart charger on it and it constantly indicating no battery, charging, no battery, etc. The connection was too loose to provide stable power.

I also changed the trans pressure sensor for good measure since they are cheap and that seemed to solve the hard, delayed shift from park to drive. I replaced upper and lower rear control arms and a front ball joint, replaced front rotors, flushed fluids (brakes, PS, rear diff and x-case were really grimy). The dealer recently replaced the trailer hitch with an OEM unit and the airbag module and both impact sensors under old recalls that were never done. I think they spent a lot more on this KJ than I did.

My buddy drove it about 120 miles one day and going up a long steady hill he said it bucked one time toward the top when shifting and then the AC didn't work for a while, everything was fine when he shut it off and restarted it. I noticed that bucking one time as well when driving it, but neither of us could tell whether it was the transmission shifting oddly (I know these valve bodies are flaky) or if it was a fuel starvation issue. No codes from that so hard to tell for sure. I have a friend with an injector machine, I just have to get time to yank them out and take them over to him to clean and test. I also have a new Mopar filter and OEM fluid for the transmission, although the stuff in it now is still red and looks good. So I just need to figure out this startup steam issue and finish the maintenance on it.

It was much better equipped (Limited, leather, sunroof, 4x4, A/C and all windows work!) than the 2wd Sport with the locked engine so I got rid of that one and kept this one. The other one had the engine disassembled and was a (bigger) basket case, and being 2wd wasn't really desirable to me. The missus wasn't having me have two of them sitting around waiting for me to get around to it.

 

[Johnny O]

Have you had the radiator flushed? Another common problem is folks didn’t use HOAT.

 

[mikelikesbbq]

Have you had the radiator flushed? Another common problem is folks didn’t use HOAT.

Not yet, I plan to do so but figured I better fix this leak or whatever it is first before putting fresh coolant in.

 

[Johnny O]

Not yet, I plan to do so but figured I better fix this leak or whatever it is first before putting fresh coolant in.

Might be worth doing now since it isn’t eating fluid. Often the previous owners dump in whatever is cheapest which causes all sorts of issues. Since it is minimal now, a flush and a fresh load of HOAT may clear up the issue

 

[mikelikesbbq]

I guess it's worth a shot, I can always recover most of it if I end up having to open it up. It looks like it might be original coolant, but it's hard to tell what happened over the past 19 years so anything is possible. It's nasty, that's for sure! Looking forward to things slowing down a bit over the holidays so I can tinker again.

 

[Johnny O]

I guess it's worth a shot, I can always recover most of it if I end up having to open it up. It looks like it might be original coolant, but it's hard to tell what happened over the past 19 years so anything is possible. It's nasty, that's for sure! Looking forward to things slowing down a bit over the holidays so I can tinker again.

Right there with you brother. Had similar issue with mine, a flush and a few miles cleared it up for me.

 

[mikelikesbbq]

That's Great to hear, I am not really wanting to do a HG on this! Thanks for your insight.

 

[mikelikesbbq]

Quick update. I did a system flush and refilled with the right coolant and a dose of K-Seal. I also put my borescope into the radiator and checked it out and found that it was spotless inside, must have been replaced at some point. Makes me feel a little safer using a sealer as they are more likely to clog up a crusty system than a clean one. Within a few starts, the steam and coolant smell in the exhaust stopped and it has been perfect since.

Now, I seem to have a transmission issue to work on....