User 41221

I am guessing I am about to lose a head gasket. I've noticed an increase in the amount of exhaust (white and wet) out the tailpipe recently, and was hoping its just due to the changing seasons. After the car gets truly warmed up, it seems like it goes away, but over the weekend, the low coolant warning light came on. There are no apparent external leaks, and I have all new hoses/water pump on the car within the last 1,000 miles or so.

I checked the coolant reservoir and it was indeed a bit low so I filled it and ran the car for a bit, but the coolant warning did not go out. I haven't checked the radiator cap with a pressure tester yet but it was replaced at the same time as the other parts, so I suspect it should still be good.

Any comments/suggestions?

BRB-83-911SC

Prior to my head gasket failure, I noticed more white smoke/vapor on cold starts than usual at warmer ambient temperatures than you would expect to see it, and like you describe, it went away once some heat was in the engine. I also began to notice the smoke/vapor on warm starts too, dissipating within a minute or so. Then the low coolant warning, with no visible signs of a leak. Finally, during a drive, the breach opened up with a large smokescreen. I shut it down immediately and started planning for the engine pull.

In my case, it was a gasket breach between the water jacket and cylinder 5. When I pulled the heads, #5 was full of coolant. I never had oil in the coolant. Presumably, prior to the full breach, coolant would leak into #5 after hot shutdown while the cooling system had residual pressure, and this coolant would boil off shortly after start up.

I would pull your plugs now to see if one is cleaner than the others - this would indicate steam cleaning. Also, crank the engine with the plugs out to see if any coolant is forced out of one of your cylinders.

There are many other possible causes for coolant loss, but the excess smoke/vapor on cold start-up would concern me - especially if the ambient temperature is above 50 degrees F.

Here is a picture of the head clearly showing the gasket breach, and here is a thread covering this saga. I hope you find a different cause with an easy fix.

https://rennlist.com/forums/showthre...ferrerid=34007

AO

+1 on Brian's experience. The coolant likes to eat the aluminum in the heads and cause the breach. No way to fix it except to pull the head and get it fixed that way.

User 41221

I have pretty much resigned myself to the fact that it would make the most sense to pull the engine and get it all done once. That will also take care of some pesky oil leaks and I might also update to the MSD headers and a crossover exhaust pipe.

Its only time and money, right? lol

BRB-83-911SC

I would rule out other possibilities for coolant loss before concluding it's the head gasket. I was in the process of doing just that when it "let go" and my start-up smoke became a full-on smoke screen; once it did let go, it was painfully obvious. However, a plug reading *may* confirm you are burning coolant.

Hopefully, if it is a head gasket leak, you will get lucky, as I did, and it will be "just" a gasket failure with no head mating surface damage.

BRB-83-911SC

I'll add that I would pull the plugs sooner than later, after the car has sat overnight or longer, and check for steam cleaning of the plugs and coolant in the cylinder. You don't want a cylinder to fill up with coolant, and then try to crank a hydro-locked engine.

Jetdriver69

If you do pull the engine for the head gaskets and decide to rebuild, you may be better off getting a 5.0L short block from 928 International and building a hybrid.

I had a dead cylinder on my 82 and rebuilt the whole thing while I was at it. OEM piston rings for the 4.5L are uber expensive and very hard to come by.

I found a entire set from 911UK for a fraction of the stateside costs, but still expensive and I think I just about cleaned out their stock.

I should have went the hybrid route with rebuilt 4.5L heads on a 5.0L block and the cost savings on the rings alone would have paid for the short block and the machine work to fly cut the pistons.

BTW, my head gaskets were just about gone on the 4.5L with 83K miles, but did not leak.

Just something to think about….