TR6 TR6 Blown Head Gasket Symptoms

[sebarnes]

Hello all, My 76 TR6 has refused to run better after almost two years of here and there attention while sitting in the shop. After rebuilding the carbs, new fuel pump, fuel tank cleaning, new exhaust system and general futsing around, she runs worse.

Would you mind describing some symptoms of blown head gaskets? Things such as, oil color, exhaust color and smell, compression would be very helpful.

Your observations are very much appreciated!! Thanks, Scott

 

[Dale]

I drove my TR7 for five years with a head gasket that was blown behind cylinder four into the water jacket. When the water pump seal went away and I was forced to tend to that, I addressed the cylinder head also. An amazing number of symptoms dissappeared including a clutch problem at starting off. After being in denial for so long I sure wish I had checked the head gasket earlier. The odor of the exhaust alone should have convinced me, as well as the cooling system not operating properly. Not to mention the poor power and fuel mileage. I kept insisting that, since I wasn't getting coolant in the oil in the form of milky oil I was OK. Even when an oil analyses showed coolant I persisted. But, alls well that ends well. I hope that any of this will pertain to your 6. Good Luck.

 

[hondo402000]

another sympton would be steam coming from the exhaust but the only way you could see that would be following the car, but then you would expect the water level to drop in the radiator and after 2 years you would know if you are constantly adding water, or like stated if water is getting in the oil it turns milky

Hondo

 

[TR3driver]

The symptoms can vary a lot, depending on where it is leaking, and how badly.

If it is blown between two adjacent cylinders, you may see only low compression on those two cylinders. (Compression readings are relative, so just compare them to the average of all cylinders. Within +/-5% is good, +/-10% is OK, worse than that means you're ready for a rebuild.)

If it is just leaking (not badly blown) into the water jacket, you may not notice any symptoms except the water level in the radiator always being a little low after a run and maybe one cylinder that always seems cleaner than the others. All of my Triumph head gasket problems have fallen into this category. The best test for this is to check for excess CO2 inside the radiator, which is a standard test that any radiator shop can do for you at a modest cost. Cost me $18 in 2005 to learn my Stag headgasket was leaking. Then I bought the tool on eBay for about $30, so I could do future tests myself

 

[poolboy]

Tell us some of the symptoms you are seeing with your 76, Scott. Something more than "she runs worse"; maybe we can put you on the right track.

 

[sebarnes]

Hi all, The TR6 has spent better than 6 months under cover in the garage (parked because after a ton of my work, it still ran rough). Two days ago I got her ready to fire up to do a shift of projects in the garage. Oil that was fresh 18 months ago (and less than 150 miles) is observed to be black. Fired her up and one side of the exhast (as always) has a mostly white smoke that never really goes away. Parked her out of harms way and let her idle. Fixed a fuel leak by tightening a line nut on the new fuel pump. Ran her up and down the parking lot and let her idle some more. Got up to temp, everything the same, rough running like a bad or stuck valve.

Yesterday fired her up again and my thought came to bad head gasket when the exhaust smelled just like brown sugar getting burnt. Having run her to temp the day before seems to have left coolant in a cylinder that left the sugar smell when fired up. Sound like anything anyone else has observed?

Thanks, Scott

 

[TR3driver]

But you aren't losing coolant ??

Normally I would say that is definitely a coolant leak (head gasket, cracked head, even a cracked block), since "white smoke" is usually steam. But you would have to be losing coolant.

What do the plugs look like?

 

[Guest]

What kind of white smoke? Does it hang around for a while or almost disappear instantly? How old is the fuel?

 

[Geo Hahn]

...Yesterday fired her up again and my thought came to bad head gasket when the exhaust smelled just like brown sugar getting burnt...

Yep, a very distinctive smell -- always makes me hungry for pancakes.

My guess would be that you are losing coolant but have not driven enough to lose enough to tell by casual inspection.

 

[sebarnes]

Hi all, Fuel is fresh and from a clean tank. The white smoke does dissapate soon after leaving the pipe. not a cloud but a constant, noticeable smoke. Coolant level has not dropped noticeably, agreed that the use just has not been there.

Does a compromized head gasket result in bad idleing, poor power and rough running?

The anti-pollution system of the 76 has been "modified" over the years. The previous owner (deceased) is said to have never got this car to "run right". Local wrenches have tried to "tune it". I have rebuilt the carbs, balanced them til I'm satisfied, and still no better.

Need to get this baby running right. Head gasket? Vacumn system? Timing chain? What would the top three TR6 rough running engine issues be?

I am very optomistic,,,Thanks, Scott

 

[poolboy]

After the engine has warmed up, (watch the dash gauge), and once the gauge needle is at the middle and if the smoke is still blowing out the back. put a piece of glass or a mirror near the tailpipe in the smoke/steam. Whatever is shooting out the exhaust will condense on the glass. You should be able to differentiate oil from water droplets..
But the engine must be thoroughly warm because a cool engine will have water condensation in the exhaust, head gasket blown or not.

Top 3.
Ignition components
Burnt valve
Vacuum leak
There's more, but the top 3 you asked for...in my mind, at least..

 

[TR3TR6]

If it is a blown head gasket, I wouldn't be running the engine very much. I had a bad experience doing that. When mind blew, it was like a white cloud coming out of the exhaust. The engine ran fine. I parked it and let it set for a couple of days. What happened was the antifreeze drained into the piston cylinder and filled it up. When I went out to start it, the water in the cylinder caused the piston to kick back and I broke a tooth off of my flywheel where the starter engaged it. I was very lucky it didn't break something else.

 

[TR3driver]

What would the top three TR6 rough running engine issues be?

Thing is, if it was something common, one of those people would have already found it.

The symptoms certainly sound like a blown head gasket, so my next step would be to pressurize each cylinder in turn with shop air, and see which one blows into the cooling system. Then yank the head and see what is going on.

But if you don't want to tackle that without exhausting all other possible avenues first, then I would go over the modified emission control system and make sure that the result makes sense. Pay particular attention to the carb bowl vents, as blocked vents can cause all kind of weird symptoms. On a 76, there is a valve on the side of the carbs that connects the vent to either the air filter (through a hole in the face of the carb), or at idle to a port on the side of the carb that normally vents through the carbon canister. That port has to be open to the atmosphere somehow. If it is hooked to a canister, make sure the filter in the bottom of the canister is open and the canister isn't flooded with fuel.

There are also ports on the sides of the carbs that normally link to the rocker cover & carbon canister. If that stuff is disconnected, block off the ports (otherwise they leak vacuum).

Speaking of vacuum, also look for vacuum leaks, particularly in the line to the brake booster (or the booster itself), and the line originally to the solenoid on the bottom of the carbon canister.

 

[svtmikey]

Pressuring the cylinders is called a "leak test", but to do it properly you need a set of leak test gauges (leak down tester). You do one cylinder at a time, rotate the engine so the valves in the cylinder you are checking are closed,and watch the guage. All cylinders will leak, but the guage is graduated from OK to accetable to bad. You also listen for where the air is leaking from.
For example, if you hear hissing out of the exhaust, you most likely have a bad exhaust valve. Out of the radiator, most likely a head gasket, Out of oil filler cap, maybe valve guides....etc...pretyy easy to narrow down.
You also may need to make sure the engine doesn't spin from the compressed air.

This test is much better than a compression test which we rarely do anymore, as I acutally tells you where the problem is.
If you are getting sweet smelling white smoke though, I would think head gasket.

mikey

 

[TR3driver]

Pressuring the cylinders is called a "leak test", but to do it properly you need a set of leak test gauges (leak down tester).

Might not be "proper", but IMO simply pressurizing the cylinders (each in turn, with the valves closed as mikey says) will give you the information you need. If you have one of the compression gauges that screws into the plug hole, usually it can be disassembled and turned into an air line adapter. Mine has 1/8" NPT threads on the hose, so it's easy to install an air line quick connect in place of the gauge. Some of them even come with a quick connect

Screw it into the cylinder, then connect the air line. When you find the cylinder that is leaking into the water jacket, you'll see the water spray out.

A leak down tester will tell you how fast it is leaking, which is a useful metric if you are looking at rings or valves. But any leak at all into the cooling system is reason enough to tear down the motor, so it really doesn't matter if it is 1% or 10%.