TR6 Diagnostics

UNDER CONSTRUCTION!

- Engine Trouble -

The Triumph 6-cylinder 2500cc engine is, contrary to popular belief, quite reliable if maintained regularly. It must be remembered that when these cars were designed, much less built, regular automotive maintenance on a scale unimaginable to today's buyer of the 100,000-mile-between-tuneup Northstar vehicles was commonplace. That said, however, things do go wrong! The first rule: Don't Panic. Generally, most problems with the Triumph 2500 powerplant are repairable with a modicum of work (and money, of course; but maybe not as much as you'd think). While many of these engines are by now in need of a rebuild (if they haven't already had at least one) many problems can be fixed much more simply.

My TR6 won't start.

When I turn the key, nothing happens.
- If by 'nothing' you mean just that, i.e. no clicks or movement, this sounds like an electrical problem. Jump to the Electrical Starting Problems section. If you have been driving your TR, and you stopped and now it won't do anything, try engaging the gears and pushing the car to rotate the engine slightly. Now try. Sometimes the starter motor can develop wear spots which the engine likes to stop in contact with; moving the motor can sometimes help.
When I turn the key, the car cranks weakly and/or makes a strange mechanical noise.
- The first suspect in this case is the battery or starter. Jump to the Electrical Starting Problems section; if that doesn't help, continue. It's possible that your starter is mechanically weak; if it's getting enough power, then it may be seized or have internal problems. Replace the starter, or have a look at the SOL Starter Guide.
When I turn the key, the car turns over but won't start.
- I'll assume that you've checked for killswitches and fiddled with the choke settings. The three things an engine needs to run are Fuel, Air and Spark (and compression). For Spark, check the Electrical Starting Problems section. If that doesn't help, continue on below.
- Check the inside of the distributor cap and inside the plug wire connectors for moisture. In areas with high humidity and temp. variations, you may see condensation inside thses locations, which will prevent the motor from catching due to interrupted spark. Dry them throughly and try again. If the car hasn't been sitting that long, check into replacing the cap and/or the plug wires.
- Check to make sure the motor is getting fuel. After several tries, you should be able to smell raw gas coming from the tailpipe, although this isn't guaranteed. If you have a carbureted engine, the surest way to check this is to make sure the carburetor float bowls are full. If you have a P.I.(Petrol Injected) TR6, have a look at Egil Kvaleberg's Lucas P.I. System Page for diagnostic tips. Otherwise, check the float bowls. Are they full?
  - No: There is a problem with your fuel flow. If you have the original style fuel pump, try to prime the fuel system using the priming lever underneath the fuel pump. The lever is a flat spoon that can be pulled up against the bottom of the fuel pump. If you have a clear fuel filter, see if you can see fuel flow. Can you see fuel flowing?
    - No: Check your fuel pump.
    - Yes: Check to make sure it's reaching the float bowls. If it's not, you may have a clogged fuel line after the pump or have a problem with one or both of your carburetors. Remove the fuel line to each carb and check the fuel flow. If it flows, your carburetors may be having trouble; seek assistance with them; also, it's possible that the fuel pump is bad and only working with the manual prime.
  - Yes: If your float bowls are full, it's possible that your carbs are misbehaving, especially if you can't smell raw gas in the tailpipe. Check your carbs. If you're pretty sure your engine is getting gas, continue.
- Okay, your engine is getting gas. Is it getting spark? Check this; take one of the spark plugs out and position it (with lead attached) so that its base is positioned near the engine block. (If there is wet gas on the plug, then you know your engine is getting fuel OK.) Make sure there is no fuel on the outside of the engine, in the air, or on you. Wipe the plug clean. Crank the car. You should see fat sparks jump from the spark plug to the engine block. Do you?
  - No: Jump to the Electrical Spark Problems section.
  - Yes: Continue.
- You're getting spark. You may want to check a couple other cylinders; although the engine won't run at all if only one works, if three or more work it should at least almost catch. Next possible culprit: not enough air in the mixture. This is unlikely; usually, air feed problems mean poor running, not complete failure to start. However, you should check the air cleaners and carbs for air flow. Make sure nothing is obstructing the airflow into the filter. Make sure that the filter is passing air by removing it and trying again. It's also unlikely that you have no compression, unless you've cracked your head! If the car was running, and now isn't, this probably isn't your trouble. If you've checked the electrics and the fuel, seek assistance.
When I turn the key, the car sounds like it's almost starting but won't catch.
- Run the 'turns over but won't start' checklist above. You should do the spark check, but you may want to leave it until last; even with two cylinders not firing, my TR6 starts and catches. It just then sounds horrible. :-)

My TR6 won't idle correctly.

It idles rough and may stall when coasting or stopped.
- Once possible cause of this that I've seen is a vacuum leak on those cars with a vacuum-adjusted distributor. As a test, if your car is one of those, remove the vacuum line from the distributor and see if the idle changes note or gets worse. If not, you may have a vacuum leak; listen around under the hood and under the pedal box for a hissing sound.
- One culprit of a vacuum leak that's not immediately obvious looking at the engine is the brake system. The Brake servo utilizes the manifold vacuum to provide braking assistance to the driver's pedal. If the idle problem is affected by the application of brakes, then you probably have a leak in the front seal of the vacuum servo; see a manual for more information. If the leak is constant, still take the time to listen very carefully to the brake servo to determine if there are any hissing sounds. If not, try removing the vacuum line from the servo and blocking off its end. If the idle improves, you may have a bad seal or diaphragm in your servo.
- Check this document for more information.
It idles too fast / too slowly / at varying speeds.
- Check here for information about bad idle and stalling.
It 'diesels' at shutoff.

My TR6 won't run smoothly/continuously.

It runs rough at all or non-idle speeds
It staggers under acceleration.
It stalls/runs poorly after long driving periods.
- If your TR6 stalls or idles/runs roughly after the engine is hot, there are a few possibilities. First, do you have an electronic ignition in your car?
  - Yes: If your TR6 refuses to run above a certain temperature, your electronic ignition control unit may be overheating. Try relocating the control unit to place it further from heat sources such as the engine block and exhaust piping. Against the inner fender on the LH side (opposite the exhaust/carbs) may work. Insulating it may not be a good idea, because the unit itself produces heat which will be trapped by the insulation. If this doesn't help, continue.
  - No: If you don't have an electronic ignition, continue with the checklist.
- Do you have a Petrol Injected (P.I.) TR6?
  - Yes: The P.I. control system may be overheating. Check Egil Kvaleberg's Lucas P.I. System pages for information on troubleshooting this system.
  - No: Continue with checklist.
- Your carburetors may be overheating, causing fuel in the floats to vaporize and disturb your fuel flow. Try placing insulation between the exhaust header and the carbs, especially if the carbs are hot to the touch after a long drive. Warm is OK; hot is not. If this doesn't fix the problem, continue.
- -to be extended-

My TR6 runs too hot/too cold.

It runs too hot.
- First of all, what's normal? If your gauge is reading correctly, your should see your temp needle hang out around the middle of the dial, drifting upwards when stopped in traffic. TR6's should have a radiator shroud in the engine compartment to channel cool air over the radiator. These resemble three panels of plyboard or vinyl which fit create a 'duct' between your radiator front and the front grille. If you don't have one, you may wish to consider getting one. This solution is only recommended if the TR is overheating during hard use, or normal use in hot weather! Check Chris Kantarjiev's article on achieving better cooling. If the TR is overheating under relatively benign conditions, or has suddenly begun overheating, run the checklist below.
- Do you have an oil cooler?
  - Yes: Do you have a thermostat in the oil lines?
    - Yes: Check it to make sure it is functioning, and opening when warm.
    - No: Continue.
  - No: Continue.
- Check your instrumentation. Try this: check your fuel and amperage gauges. Are they reading correctly?
  - No: These three instruments share an electrical circuit (fuse) and voltage regulator. Something may be wrong there; jump to Instrument Trouble.
  - Yes: Continue.
- It's possible that your temp sensor is not operating correctly. Does it work correctly?
  - No: This may be your problem. Replace it and see if that helps. If not, continue with checklist below.
  - Yes: Continue with checklist.
- Check your thermostat. Are you running the correct thermostat for your climate? (Summer-160deg; Standard- 180deg; Winter- 195deg)
  - No: Replace with correct thermostat. If that doesn't help, see a mechanic.
  - Yes: Your thermostat may be inoperative. Test it or replace it. If this doesn't help, continue.
- Check your radiator flow. Make sure that your radiator and lines are not clogged; try running the engine with a continuous water supply (powerflush?) and see if the flow rate is OK. Warning: never put a continuous cold coolant flow directly into a hot engine! Wait until it is cool, and then start it and warm it slowly. Does your coolant flow correctly?
  - No: Have your radiator rodded out and check/replace your hoses. Did this fix the problem? If no, read the next line.
  - Yes: Hmm. You've gone beyond my limited expertise. Ask the list or your local mechanic.
It runs too cold.
- Do you have an oil cooler?
  - Yes: Do you have a thermostat in the oil lines?
    - Yes: Check it to make sure it is functioning, and closing when cold.
    - No: If it is cold outside, there should be a thermostatically-controlled valve to prevent oil from traveling to the cooler until the engine oil has reached operating temperature. Otherwise, the oil may remain at too high a viscosity. Although this may result eventually in too *high* an operating temp, it may mean a longer-than-expected warmup time and excessive wear.
  - No: Continue.
- Check your instrumentation. It is unlikely that a TR6 is *actually* running cold, especially in warm weather. Try this: check your fuel and amperage gauges. Are they reading correctly?
  - No: These three instruments share an electrical circuit and voltage regulator. Something may be wrong there; jump to Instrument Trouble.
  - Yes: Continue.
- It's possible that your temp sensor is not operating correctly. This happened to me; and I got a minimal temp reading until I replaced it. Check your temperature sensor first, it's cheaper. Does it work correctly?
  - No: This may be your problem. Replace it and see if that helps. If not, continue with checklist below.
  - Yes: Continue with checklist.
- Check your thermostat. Are you running the correct thermostat for your climate? (Summer-160deg; Standard- 180deg; Winter- 195deg)
  - No: Replace with correct thermostat. If that doesn't help, see a mechanic.
  - Yes: Your thermostat may be inoperative. Test it or replace it. If this doesn't help, seek the assistance of the list or your local LBC mechanic.

My TR6 makes strange noises while running.

It makes noise related to engine speed.
It makes noise related to vehicle speed.
It makes noise related to road conditions.
- See Mechanicals:Suspension Noise.
It makes noise at startup.

My TR6 produces strange-colored/excessive exhaust.

It produces black smoke.
It produces white smoke.
- White smoke generally means that there is coolant in your combustion. The first thing to do is check the quality of your fuel . Is there water in it?
  - Yes: Drain your tank and fuel system low spots and optionally add Dry-Gas or equivalent. Check your fuel cap for leaks. Don't leave your car sitting for long periods with a partially-full tank.
  - No: Did you put additives in the tank recently?
    - Yes: Discontinue use. To be safe, continue with checklist.
    - No: continue checklist.
Okay, perhaps there's a problem in your engine. Check your coolant by continuing.
- Has the car been using excessive coolant?
  - Yes: Check the radiator for leaks. Are there any external leaks?
    - Yes: Fix radiator; check exhaust. Is it still white?
      - No: OK!
      - Yes: Continue with checklist.
  - No: Drain and examine some coolant. Is there oil in it?
    - Yes: You may have a leak in your head gasket or a crack in your head. Skip to 'Remove your head.' No, the engine head, silly.
    - No: Continue with checklist.
  - Drain and examine your oil. Is there water in it? Does it have a 'whipped mayonnaise' consistency?
    - Yes: You may have a leak in your head gasket or water pump or a crack in your head. Check this tip, then refer to the Procedures page.
    - No: Continue with Checklist.
  - Remove your engine head and examine the mating surfaces. Is there damage?
    - Yes: Replace the gasket and test.
    - No: Have your head Magnafluxed or otherwise checked for cracks. Replace the head gasket.
It produces blue-grey smoke.
Bluish smoke is generally indicative of burning oil. Check to see if any oil is leaking into your combustion chambers.
It sounds far too loud.
- Check your muffler for holes. Any visible?
  - Yes: Replace the muffler, old chap.
  - No: Continue with checklist.
- Check your exhaust piping under the car (single-pipe through 1971; double '72 and after) and downpipe. Is it damaged?
  - Yes: Replace piping.
  - No: Continue.
- Check your exhaust headers. Are they attached firmly to the engine? Are they in good shape?
  - Yes: Maybe you need a quieter muffler. If you have a Monza or other aftermarket, check out the Falcon stainless system. I like mine.
  - No: Repair or replace your header.
It sounds far too quiet. (:-))
- Get a louder exhaust! Be sure to obey emissions and noise regs for your state/region. Then go set off some car alarms.

My TR6 runs anemically. (i.e. below 110hp, you racers).

It staggers under acceleration.
It won't accelerate quickly.
It won't climb hills.

My TR6 smells like gasoline.

These cars tend to smell like gas a bit, especially with covertible tops. If the smell is not pronounced, and is constant, don't worry about it too much. Check under the hood; is there a pronounced raw gas smell there? If so, then you may have a problem; jump to the Body Fuel Tank checklist. Also check the gas cap for leaks. If there is a serious raw gas smell near the rear of the car that isn't related to it running, run the checklist.

My TR6 oil pressure doesn't look right.

What's Normal oil pressure?
- Oooh. It appears that if you're getting over 15psi at idle and 45 at speed (highway) with the engine warm, then you're OK. Note that when the oil is cold the pressure may be noticeably higher.
My Oil pressure is too low (lower than the above).
- There are several possible causes. Start with the simple. Flick the oil pressure gauge with your finger while running the car to see if it's sticking, or otherwise test the gauge. Did the reading slip to a normal range?
  - Yes: Looks like that was your problem. Stop here, but keep an eye on it, testing frequently.
  - No: Okay, let's move on.
- Check your oil level using the dipstick. Is the oil level adequate (at/above the top mark)?
  - No: Fill with oil. Make sure you use the same oil rating as is already in the car (e.g. 10W40 or 20W50). Re-warm the car and check the pressure. Is it noticeably better and does it stay higher after warming up?
    - Yes: Looks good; just to be sure, check the oil color. If it's black, change the oil and filter; you may have suffered breakdown. Use synthetics if possible. Test. If OK, great. If not, move on.
    - No: Check the oil color. If black, change the oil and filter and test; if OK, great but keep an eye on it. If not, move on.
  - Yes: Continue with checklist.
- If you haven't already, change your oil and filter. While doing so, check the oil pan for any residues. Silvery mush, or metal fragments, can mean problems in the engine! If there's anything other than yellow-brown or black oil, have it checked by a professional, or continue by checking bearings and clearances. Check getting more help if necessary. If the oil looks OK, change oil and filter and test the car, re-warming it. Does the oil pressure look better?
  - Yes: Great. Keep an eye on it, though.
  - No: Continue with checklist.
- If you haven't yet, run the checklist below under Burns/Loses Oil.
- You might try checking the oil pump, although I'm not sure how to do that other than by replacing it.
- If that didn't help, check out getting more help. Check some other owner's experiences at VTR.
- Some other possibilities include worn bearings or thrust washers, and other internal maladies. Have your engine evaluated by a professional mechanic.
My oil pressure is too high (higher than the above).
- You probably should only worry if the pressure is over around 90psi, or if it doesn't drop noticeably after the car has warmed up. If the former, you may wish to check the pressure relief valve; see a manual for more information. If the latter, flick the gauge with your finger sharply; see if the pressure reading drops. If so, then don't worry; most oil gauges I've seen demonstrate some 'stickiness.' Think of it as character; it lets you calmly flick the gauges when you start up like those dashing young men in Battle of Britain movies.
My idle pressure is much, much lower than cruise pressure.
- One possible cause of this, if your cruise is somewhere normal (like over 45 psi) but your idle is waaay low (below 15-20) is bad oil lines. Mike Passaretti, on the triumphs list, notes that if you are using plastic oil lines anywhere, they can heat up and expand. He recommends replumbing with copper.

My TR6 burns/loses too much oil.

It uses more than 1 qt./300 miles.
It leaks oil onto the pavement.
- Good, it's a TR. One authenticity test passed. Seriously, these cars generally will leak a bit of fluid in the best of times, and used engine oil can make a great underbody protectant. If there's a lot of oil on the ground and your car is losing oil, then continue.
- First, check your oil drain plug and oil pan. Is the plug missing or leaking, or is the pan damaged? Is there oil leaking around the top of the pan?
  - Yes: Repair or replace the pan and/or drain plug. If there is oil leaking from the top of the pan, replace the pan gasket.
  - No: Continue.
- Make sure of the source of the leak. Is it coming from the join between the engine and transmission?
  - Yes: You may need a new rear main seal. Although the seal is cheap, you'll have to remove the transmission (disconnect and drop it, at least) or engine to replace it; it may be cheaper to simply live with the problem and feed it oil until you have a more compelling reason to drop the drivetrain.
  - No: Continue.
- Is the leak coming from the transmission or differential themselves?
  - Yes: Jump to the Drivetrain Leak checklist.
It leaks oil into the engine compartment.
- Try to trace the leak source. If it's not immediately obvious, clean the compartment and run the engine while watching with eye protection. Or continue on. Start with the oil filler cap; is it on properly and does it fit snugly?
  - No: Replace it.
  - Yes: Continue.
- Check the seal between the valve cover and the head. If it is leaking, replace your valve cover gasket and make sure the cover is securely fastened.
- Check the seal between the head and the engine block. If it is leaking, remove the head and replace the head gasket. Also check the head and block mating surfaces to make sure they are flat and undamaged.
- If the oil is at the back of the engine compartment, check the join between the engine and transmission. If oil is escaping there, you may need a new rear main seal (a few dollars, but involves disconnecting the transmission or engine).
- If this hasn't done it, check your dipstick. Is oil coming out the dipstick hole?
  - Yes: You may have overpressure in your crankcase. This may indicate problems with your piston rings, which might allow combustion pressures down into the lower end. Seek assistance.
  - No:

How can I tell if the Thrust Washers are OK?

I don't have the car apart/don't want to.
- Testing the Thrust Washers in a TR6 engine - important! This is a Kentucky Windage measurement, but it works.
I'm doing a rebuild and can look at them.

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