White Exhaust Smoke With A Twist (1 Viewer)

[3Speed40ForLife]

Hi All,


As stated in the title, I'm getting white smoke out of the exhaust on my 1/72 FJ40 with stock F engine (excluding the DUI electronic Distributor).
At face value it's seems like a head gasket leaking coolant into a cylinder. (smoke smells slightly sweet) But there's a twist that I can't figure out. Before I get elbow deep into a head gasket replacement. I would like to be sure that I'm headed in the right direction.

The Twist:
On a cold start-up the exhaust is clear. No white smoke. I can drive along and stop at a light and nothing white is coming from the exhaust. I've pulled over and got out to inspect the exhaust to make sure of this.
On a hot restart (like stopping for gas and then leaving the gas station) I get a lot of white smoke (picture attached of a hot restart). This smoking will last for 45-60 seconds and then quickly clear up. After that, there is no smoke at all. Again, I've checked closely.

Aside from the exhaust smoke, there are no visible leaks on the exterior of the engine itself. The engine oil does seem to have some watery liquid in it. The spark plugs don't seem to be fouled, but I'm also not driving it a lot because of this issue. They might not have enough hours on them to get a good reading. Idles smoothly but if I pull away from a stop it initially chokes, and then gets moving. At speed it seems like it's down on power when I put my foot down.


Sorry for writing a novel. Trying to give a clear picture of the situation.
Any advise on the issue would be very helpful.
Thanks!


Recent Car History:
- Had overheating issues. Ended up replacing the radiator and water pump. Replaced thermostat gaskets. No further overheating issues.
- Replaced ignition wires and spark plugs.
- All fluids changed

 

[charliemeyer007]

So is your coolant level dropping? Water in the oil usually makes the oil look milky. Overheating can easily case the head gasket to fail - you might try retorquing the head bolts while its cold and see what happens.
Coolant in the combustion chamber can steam clean the plugs so to speak.

 

[Pighead]

Compression test?

 

[Grayscale]

Only on a cold motor, take the radiator cap off. Does an idling engine make the coolant bubble up?

The spark plugs should tell you if it is coolant, or oil. The overheating in the past is certainly a bad thing. Any additives in the oil, like ATF or Marvel Mystery Oil? Most of these old engines need valve stem seals; my 2F looked like your photo, not long after I got it spinning. I've torn into three 2F heads, two, with the early or F-style seals, but, all three needed it.

 

[3Speed40ForLife]

Thanks for the all the replies. Once I get home today, I'll dive into some of these suggestions and report back.

 

[3Speed40ForLife]

charliemeyer007 - Coolant level is dropping suspiciously. Not very much, but noticeable. I grabbed the wrong torque wrench from the shop today. I'll have to bring the larger one home tomorrow.

Pighead - I found my compression tester. Never actually used it. Got it when my dad sold his 40. What would be considered a bad reading?

Grayscale - Took the cap off and idled the engine. I was expecting bubbles but got nothing. I do use a little Marvel every now and then.


This one is definitely a head scratcher for me. I don't feel like I'm seeing the clear signs of a blown gasket.

 

[charliemeyer007]

More than 120 in every jug would be good for a cold older engine. The same +/- 5/10 in all is a real plus.
A blown head gasket can leak coolant into the oil or the combustion chamber.

 

[Grayscale]

I had some Marvel Mystery Oil that I used to clear carbon from piston rings, I added it thru the spark plug holes, and some in the crankcase, that was when I noticed smoke. Every startup after that I had more smoke. It really cleans-out sludge, who knows what else it does? It would be a good bath for an oil pump screen, on a sitting engine. IIRC the dipstick was really shiny below the oil level that had Marvel, prompting me to clear the upper part manually. There was a thread where a chunk of carbon shorted out a spark plug, Mudder thought his engine was toast, before he found it. I likely had a chunk of carbon get tossed into the exhaust, that smoked like you wouldn't believe, in traffic. I pulled over immediately, but, by then the exhaust was clear. I'd imagine that the Marvel could contribute to smoking, as after I drained the crankcase, the smoke cleared up a bit, yet I still needed new valve stem seals

With the valve stem seals, it was like a big puff of smoke at startup, then kinda clear, then more with deceleration after throttle.

What do the spark plugs look like after you clean them with a steel brush, about 200-grit silicon carbide sandpaper, and some course steel wool, and then run the motor for a bit?

 

[SteveH]

Does this white smoke have that icky sweet antifreeze smell, or does it smell more like rich fuel or oil?

 

[3Speed40ForLife]

Does this white smoke have that icky sweet antifreeze smell, or does it smell more like rich fuel or oil?

To my uncalibrated nose, it's icky sweet.

 

[SteveH]

Sweet = Likely coolant, then.

Buy/rent/borrow a cooling system pressure tester, and put the cooling system under 15 psi (done at the radiator cap) for an hour or so, and see if it holds. If it doesn't, then pull all the plugs and see if any cylinders have coolant in them.

 

[cstav86]

Is there white goop in your valve cover cap? That can be another indication of blown head gasket.

 

[3Speed40ForLife]

Well... Mystery solved. Mostly thanks to Pighead's recommendation to do a compression test.

Never having done a compression test myself, I just followed the instructions which told me to remove all plugs after I had brought the engine to full temp. No sooner than the initial crank dose a tablespoon of coolant shoots out the #4 cylinder. I gave it another turn-over and another table spoon comes out. A third/fourth/fifth time produces only a dribble.
One of those moments that was so stupid simple that It makes you say... How come I didn't think of that sooner!?

It appears that the leak is so small it needs to build-up until a hot restart to make a cloud out the tailpipe. But not enough to maintain a visible cloud once the initial build-up is pushed out.

Thanks everybody for the help!

 

[Grayscale]

Let's hope that it is a bad head gasket, and / or incorrect head-bolt torque. Flatness on the deck and head is of concern, as is cracking on the head. How bad was the overheating issue, or how far was the temp gauge?

 

[Pighead]

Well... Mystery solved. Mostly thanks to Pighead's recommendation to do a compression test.

You're too kind. It's not an original idea and you didn't even need the compression tester. You just had to pull the plugs and spin the engine.
Now you have a Golden Opportunity to pull the head, examine your cylinder walls, clean off accumulated carbon and think about a nice valve job.

 

[3Speed40ForLife]

Let's hope that it is a bad head gasket, and / or incorrect head-bolt torque. Flatness on the deck and head is of concern, as is cracking on the head. How bad was the overheating issue, or how far was the temp gauge?

I did check the head bolts and they were still at the require torque value.

On two occasions the temp needle reached the second line or slightly past as I dashed to a place I could park and allow it to cool. Not sure what value that line represents... besides bad.

 

[Grayscale]

When and how did you check the head-bolt torque? Typically, the blocks threaded holes are checked with tap, and head bolts need cleaning and oiling, each done in sequence, to get a proper torque spec. Running a tap means removal of the cylinder head.

 

[Pighead]

When and how did you check the head-bolt torque? Typically, the blocks threaded holes are checked with tap, and head bolts need cleaning and oiling, each done in sequence, to get a proper torque spec. Running a tap means removal of the cylinder head.

I'm thinking he just put a torque wrench on each headbolt and gave it a bit of righty-tighty to see if any seemed loose. Probably not looking for an accurate reading.
I don't have that tap so I just cut a slot in a spare headbolt, oiled it up and ran it in & out

 

[3Speed40ForLife]

When and how did you check the head-bolt torque? Typically, the blocks threaded holes are checked with tap, and head bolts need cleaning and oiling, each done in sequence, to get a proper torque spec. Running a tap means removal of the cylinder head.

This was a down and dirty check. I was really just looking for anything suspiciously below the torque value. The two bolts around #1 that hold the air filter housing crept ever so slightly before the wrench clicked. But everything else held fast.

At this point It's coming off anyway. I'll make a note to clean the holes out with a bottoming tap.

 

[charliemeyer007]

While you are there look at all the galley plugs. I get/install a set of valve stem seals. A real valve job or at least lapping.