New, Very New symptom - Steam in Exhaust, Coolant level way down

This evening, I started the T-100 and it started very roughly. Noticed smoke out of the tailpipe, and since it’s hot & humid in Baltimore now, I did not think it could be condensate.

It is indeed steam. Went to the radiator, and it is low (looks dry where just a few days ago the level looked fine).

Have been having likely EGR issues or some other issue that makes the T-100 start rough when warm - see previous submission: http://act…

So - where could the coolant be entering the combustion/exhaust stream (no pun intended!)?

Probably head gasket, need to have a shop look at it.
Can usually tell by pulling spark plugs and seeing which one is wet or has greenish deposits on it from the coolant. But usually something in the cylinder head area.

I agree. It’s either a head gasket or intake gasket leak. You need a good mechanic to run some diagnostic checks to find the root of the problem.

I agree, time to get it to a mechanic.

Any other places coolant could get wind up in the exhaust?

And how long before this totally screws up my engine?

Don’t put it off. Take it to a mechanic ASAP.

Make sure coolant isn’t contaminating your oil. This will ruin your engine quickly.

A head gasket leak that is allowing coolant into the cylinders is not good, but it can be managed–in the short term–by very carefully and very frequently monitoring and refilling the radiator.

But–Have you checked the dipstick to see the color and the consistency of the motor oil?
If the oil looks like a chocolate milkshake, that is a really bad sign, and the truck would need to be towed to the mechanic a.s.a.p. Once coolant begins to contaminate the motor oil, that means an immediate stop to the use of the vehicle and a careful inspection by your mechanic.

And, please bear in mind that what looks like merely a leak of coolant into the cylinders can rapidly morph into a head gasket problem that allows coolant to contaminate the motor oil. I would not delay the mechanical inspection any more than necessary, just in case your head gasket problem becomes this more serious type of breach.

Edited to add:
Goldwing–You type faster than I do!

Thanks all, the T100 is with a mechanic right now.

The T100 started right up this morning, with no more steam leaving the tailpipe. Amazing, it seems to be running smoothly - but I don’t trust it.

Last night after noticing the steam out the tailpipe and the low coolant level, I put a 1/2 gallon of water in the radiator overflow container before heading home. About half of that has worked its way back into the radiator.

Am waiting to hear what John finds with the spark plugs, oil check, pressure, fuel line check, etc. Will post the results then.

Thanks for ringing the alarm.

Back from the mechanic. Ran smoothly from his shop to my home (5 blocks away).

But then - Latest start-up - turn the key, and “Conk!” sound, no further turning of the starter. Two more times, same thing. Fourth time, it turns over and then starts. Idles roughly. “Pup, Pup, Pup” coming from the tailpipe, with steam. It’s a sunny 79 degree day here in Baltimore this afternoon.

The engine is not consistent - sometimes starts smoothly, but then it restarts rough and idles rough.

Mechanic’s checks included -
No coolant in the oil - the oil looks dark translucent brown.

Fuel pressure test was fine.

New plugs put in. The 1st plug coming out - closest to the radiator - had black all over the ceramic. Other plugs looked fine (NipponDenso), a bit yellow perhaps. Did not see anything green(ish) - got a picture of something like that?

EGR valve cleaned with carb cleaner.

Vacuum hoses checked, appear ok.

Air filter fine.

Pulled airflow unit from the injector unit - looked fine.

Thinks that the #1 injector is bad.

meanwhile, I have a few local errands to run - will be taking a jug of distilled h2o with me.

What explanation did your mechanic have for the apparent consumption of coolant?

Incidentally, adding water to the cooling system is only going to increase the possibility of overheating, thus exacerbating current problems and possibly creating new ones. I know that it is appealing to save money by adding only water if you are consistently observing a low coolant level, but by constantly diluting the remaining coolant, you are just going to increase your vehicle’s problems.

If your mechanic has no explanation for the apparent consumption of coolant, then you need a new mechanic.

That “conk” is not a good sign. It could indicate that enough fluid (coolant or gasoline) is getting into the cylinder to hydraulically lock it. The next time this happens, remove the spark plugs; disable the ignition; crank it while watching the holes; and assess or smell any liquid flying out. I suspect you will find coolant in one of the cylinders.

How the coolant is getting into the cylinder is going to take some searching. It could be a leaking head gasket; a cracked head or block; a leak into the intake manifold; or whatever. On further research I found that the 1995 T-100 has bypass water flowing through the throttle body – probably heating the Idle Air Control adapter. If that adapter’s gasket is leaking it might be going into an intake runner and eventually getting into the cylinder on the intake stroke. Just an idea.

Keep us apprised of your progress here.

On one hand, the coolant level seems to have stabilized. I do not intend on leaving the coolant as is; I thought it would be better to get some liquid in there sooner than later and only as a stop-gap measure. When the other engine issues are resolved, I will have the coolant flushed and filled anew.

The truck has not been driven much today; earlier, not so bad. It was a bit balky this evening, and the check engine light appeared for the first time in months.

Tomorrow’s another day.

Here’s the Steamy aka Down 'n Dirty:

Today, rough start, ran rough and then the temp reading was almost into the red. Stopped by auto store and picked up coolant. Took a gallon of 50/50 mix into the radiator directly and another 1/4 gallon into the overflow which was almost empty.

For the rid home, tried to start it. Conk. Conk. Single “Conk” about a dozen times, and finally the ignition turned over and engine started, rough of course. Lots of white smoke that quickly dissipated (steam).

Guess I’m on the bike for awhile.

So it’s off to a new mechanic. What am I looking at? I don’t have any leaking antifreeze under the engine compartment, so it’s all going out the exhaust. What should I tell the mechanic?

My #1 spark plug was dirty - here’s a pic of the four. Possibly all the coolant was going thru this one? A slow leak turned into a torrent? Just - I say just - a blown head or intake gasket, or perhaps something else? Any “easy” tests?

No more comments?

One more update. New mechanic pulled plugs to do compression test and had a geyser in #1 cylinder. Basic repair at this point - if it’s a blown head gasket and all other mechanicals are OK - estimate was at $1,300.

I miss my Grey Ghost.

Today, I get 'er back. $1,800+.

Guess I’ll bike it down in the rain, in this 46 degree weather! Woohoo, I get 'er back!

Let us in on the final scoop. Give us a blow by blow on what parts were replaced.


Hard to believe that you take it in for a suspected head gasket leak and he checks the air filter, fuel pressure, etc? The running rough is not the problem, the steam is the problem. The running rough is the result. Don’t check for the symptoms, check for the disease.


Head kit installed - head gasket, intake manifold gasket, cylinder gaskets.

Saw it with the valves removed. #1 cylinder was clean from all the coolant flushing it out. All others looked normal.

I think you’re confusing the two mechanics. Mechanic #1 did not think the coolant loss was significant.

Mechanic #2 went pretty much straight to the head gasket after finding coolant in #1 cylinder.