By on June 1, 2011

Newsom writes:


I am a newbie here so I am not sure that I am posing the question in the correct cyber-manner but here goes: I purchased a 2000 Nissan Frontier 4-door truck new in August of 1999. It has 112K miles and I have just replaced the clutch: it was the training vehicle for my teenage daughter. I have a son who is 13 who will also learn to drive on this vehicle, then it will be put to pasture.

When I took the truck to my mechanic to get the new clutch I told him that I smelled burning coolant when I got out of the truck. He did a pressure test and said it came from the radiator, which he replaced.

I still smell it however and I need help. There is no puddle of coolant under the truck after it has been parked. I replace about 1 quart of coolant about every two months or so but it is not disappearing rapidly. I have been resisting using the words h*** g****t for fear that he will recommend replacing them to the tune of big $$$. The smell is strongest under the hood. I don’t smell it near the tail pipe.

Please help. We cannot live without a truck in the family.

Sajeev answers:

If the oil and coolant are nice and unmixed, odds are the h*** g****t is okay for now. And I reckon for a long time to come. It’s a blessing and a course that you don’t smell it inside the vehicle, as failing heater cores are easy to diagnose, difficult to replace. This is another tough one to armchair quarterback, so I will tell you the proper diagnostic method.

Test and replace the radiator cap first.  A “soft” cap can bleed off coolant slowly enough that nobody notices, and since they are rather cheap to replace, maybe that’s all you need. But if not…

Put dye in the cooling system, take a black light to it, and find that darn leak!  I suspect its some heater hose at the firewall, sometimes those are very hard to find without the dye. But that’s usually in cars with cramped spaces, like most transversely-mounted DOHC V6’s in sedans and sporty German whips that place engine aesthetics over accessibility. The dye should work quickly and easily on a Nissan Frontier.

Good luck, I am pretty confident this is an easy fix.

Send your queries to [email protected]. Spare no details and ask for a speedy resolution if you’re in a hurry.

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37 Comments on “Piston Slap: The Last Frontier, The Dreaded H*** G****t?...”

  • avatar

    First, this:
    > I have a son who is 13 who will also learn to drive on this vehicle, then it will be put to pasture.

    doesn’t seem like it meshes with this:
    > We cannot live without a truck in the family.

    Anyway, my friend just replaced a leaking water pump. He reported smelling burned coolant but couldn’t trace it down. No puddle or anything. It turns out his water pump was weeping and the liquid never made it to the ground. The way he found this was by running the engine and poking his head and a light around.

    If your mechanic did a pressure test and found fault with the radiator, did he pressure test again after replacing it? You might have (or had) more than one leak. If you’re not the type to nose around yourself, take it back to the mechanic and see if he can find another…

    • 0 avatar

      In most states the driving age is 15 with parents present and 16 solo minimum. Thus a 13 year old will inherit the truck in 2 years, 2013, and will be driving it alone (and thus running into things) in 3, so the truck will be 15 years old. But it has to get there first.

      So the statement about truck necessity goes something like this:

      We need a truck. We plan on having our 13 year old destroying…err driving it. We will get a different vehicle at this point; presumably a truck.

  • avatar

    I assume this is a V6 truck? If so, the intake manifold would presumably have coolant ports that let the coolant circulate between the two cylinder heads. That is another potential leak point.

    Note that a leak there could be internal or external, so it could spray into the engine bay, or it could spray into the engine and leave the car as steam from the tailpipe.

  • avatar

    You should have someone perform a cooling system chemical test. It will test for the presence of combustion gasses in the coolant and give you a definitive answer on the “head gasket leaking into combustion chamber” issue.

    • 0 avatar

      ^^^ what he said. Would cost you $50-100

    • 0 avatar

      I have a similar but even mor strange problem on my Cadillac STS-05. One quart of coolant is gone after 7000 mi. No visible leaks. The car has been to a workshop for all types of pressure testing, fibre optic inspection, analyzis etcetera. Changed the pressure cap just in case, but it continues. It is so little so a non gearheaded person would not even notice, but I do. No trace of coolant in oil or oil in coolant. But I wiped the oil filler cap clean and now two month later if a take one finger on the inside of the oil filler cap I can taste some sweetness, ethylene glycole! My only guess is it could be the oilcooler. The oil cooler is immersed in the coolant in the cooler like on other modern cars, a minor leak could cause this?

  • avatar
    Kosher Polack

    I often use TTAC to educate myself, so pardon a wee threadjack: What makes replacing the head gasket so evil? Is it because a lot of V-engines have a lot of parts to remove in tight spaces (and God help you if it’s a FWD V6)? Lots of coolant and oil to clean up/replace? Two dozen bolts to tighten to perfect spec? I’ve been lucky to never actually have to do one, only replacing things that are outside of engines.

    I’m still young, of course.

    • 0 avatar

      It’s not a hard job, just very time consuming. I’ve done head gaskets on my OHV 4.0 Explorer 3 or 4 times over its 300,000 miles and it takes me a solid day to do it if I really hump it. I take my time and it takes about two days, but then I also clean the combustion chambers, new plugs, pull the lifters and inspect the camshaft, clean and paint parts, and replace anything else that happens to be nearing the end of its life. You will wear out your arms from turning lots of bolts of various sizes.

      FWD cars aren’t really any harder, in some ways they are easier as you are closer to the heavy head.

      • 0 avatar

        Your last line is only true if it’s an inline engine. If a FWD vehicle has a V6 changing anything to do with the back bank of cylinders is a PITA.

      • 0 avatar

        The last FWD car I did any major engine work on, was my sisters ’94 Olds Achieva. Now that ‘Quad OHC’ was a piece all right. Somehow it jumped time despite having not very many miles on it and bent all the intake valves. I seem to recall that particular car having all sorts of issues that required the head to come off a few times. About 900X harder than my ’86 Pontiac 6000-STE and its 2.8 V6, and I dismantled the 2.8 in the car, before realizing the block needed to come out so I can take the cranshaft out to replace it.

        I tried to straight up trade my sisters under-Achieva for my perfectly reliable Poncho or Explorer just to make it go away to an early death, She finally traded it in on an ’04 Envoy after Dad, me and her husband all said that we weren’t working on it anymore.

    • 0 avatar

      A head gasket job on a vehicle always brings up questions of what else should be done. That $10 gasket can end up costing $300 and days of work.

      The other considerations are:
      1. Is the head warped, and is the leaky gasket just a symptom? This requires milling the head surface.
      2. Should the valve seals be replaced? Not very expensive, but requires lots of disassembly and reassembly of the valve train.
      3. Should the valves be reground? Somewhat expensive.
      4. Should the valve guides be replaced? Again, expensive.
      5. Exhaust fasteners tend to break or round off – not fun.

      So, all these things can easily add up to a fairly big job.

  • avatar

    Anything wetness around the water pump? A lot of fear about head gaskets comes from the old days when the problem would turn out to be a warped cylinder head. Even today, it takes all the work you would expect replacing a timing belt and then some, so it’s a tricky, time consuming and thus expensive bit of work.

  • avatar

    This can be a tough one. With that many miles on the clock, it could be there are extremely small cracks in the head and block, and no amount of head gasket changes will alleviate it. This was a common occurance in Chrysler 2.5L engines – I know, I owned several. There is no cure, either.

    If that’s the case, drive it until you finally need to jack up the radiator cap and replace everything underneath!

  • avatar

    I have a son who is 13 who will also learn to drive on this vehicle

    A teen in a 11 year old pickup? Hum….

    • 0 avatar
      Ian Anderson

      Reliability, how easy it is to work on and cost are usually the things that determine what a teenager drives. I should know since I am on and I drive an ’89 S10 with a 4.3. That’s why so many people 15-20 drive old early ’90s Buicks, Corollas and pickup trucks, many of which have rust severe enough to turn the car to dust if it hits a curb. (At least with the pickup that’s easily fixed.)

    • 0 avatar

      I learned how to drive in a 1966 Chevy. Well, it had seat belts, but I doubt it was as crashworthy as a ’99 Frontier.

      All things being equal, I’d rather my now grown kids to drive modern crashworthy cars with air bags etc. but on the other hand, my two oldest kids spent many a mile in the back of a ’72 VW bus. If all they can afford is an old beater, oh well, they probably survive too.

  • avatar

    Everything I know I learned from TV. If I need a new head gasket, I’ll just use the leftovers from Lisa Douglas’s pancakes.

  • avatar

    It would be helpful to know if it was the KA or VG engine (inline 4 or V-6). The head gasket job is a completely different animal on either one. If it’s the 4, I wouldn’t sweat it. An easy DIY job for anyone that can turn a wrench and read instructions. But doing the head gasket, timing belt and water pump on the V6 can be a real beast. It is major surgery. And yes, you might as well do it all when you get up in there, because you really have to gut the thing to do it.

    The first time I did this, it was awful. The second time was only slightly less awful, as I removed everything from the engine forward, which made the job much easier.

    I am on my 3rd V6 hardbody, and will probably get a 4th when this one dies (a 95 Pathfinder with 213,000). Gotta love ’em.

    The worst part about the V6 is tensioning the timing belt. For the life of me, I don’t know why they don’t put a spring tensioner in there (like every other car I’ve ever had). Instead, there’s a plain old dumb pulley which requires an arcane ritual involving f-bombs and a set of feeler guages. And there is little forgiveness if you mess it up.

    My plan for the next time around is to attempt to fit a spring-loaded tensioner in place of the factory item. Don’t know how well that will work out, but it’s definitely worth the effort.

    BTW, at 112,000 miles, that Fronty is FAR from being ready to put to pasture. She’s not even properly broke in yet. . .

    • 0 avatar

      It must be a V6, as they didn’t make a 4dr Fronty with the 4Cyl in 2000.

    • 0 avatar

      “BTW, at 112,000 miles, that Fronty is FAR from being ready to put to pasture. She’s not even properly broke in yet. . .”

      Agreed. I have a 99.5 Pathfinder with the same VG33E engine about to roll 138k miles. The thing never gives me any problems and feels tighter than many new cars that I drive. This was the tail end of the golden age of Japanese cars and I’m now glad that I didn’t wait for the introduction of the VQ35DE, as that has been decidedly less reliable.

  • avatar
    John Fritz

    Sajeev nailed it. Dye. Black light. You’ll get it figured out. Everything else is speculation. I’ve had this problem before. That dye stuff is a lifesaver.

  • avatar

    There is another approach that doesn’t require dye. With the engine cold, connect a cooling system pressure tester and pump up the pressure to 13-15psi. Then wait. With the engine cold, small leaks won’t vaporize (which causes the “burnt coolant” odor) and you have a chance to find them. Use a flashlight and an inspection mirror to check hidden areas. Even better if you can get the vehicle up in the air, if not on a lift then on ramps (Blitz Rhino Ramps are my favorite).

    Also, just in case it IS a head gasket leak or (God forbid) a crack in the block or head, it’s not a bad idea to remove all of the spark plugs. If no external coolant leaks can be found after 15-30 minutes of pressure on the system, crank the engine and see if any liquid shoots out of any of the spark plug holes (stand clear!). If you do have coolant getting into the cylinder(s), cranking the engine over with the spark plugs installed can lead to hydrolocking your engine which will necessitate an engine rebuild.

  • avatar

    My 2000 Fronty V6 had a pesky coolant leak from one of the small coolant hoses under the intake plenum. It was actually dripping from the nipple on the idle control valve (or maybe the throttle body….I can’t recall). Hose looked fine and pulling the plenum off to get to it to replace it didn’t look like fun, so I put a small screw clamp on it in place of the stock spring clip. Been fine ever since. It dripped onto the valve cover and would get vaporized before it hit the ground, so it took a bit to track it down.

    Mine has been a great truck. About the only complaint I have is it goes through A/C hoses like crazy. I think I’ve replaced 3 on my truck in 80K miles.

  • avatar

    IIRC, the 4-door Frontier (crew cab) was never available with the 4-cylinder, so Newsom probably has a V6, which will be more problematic if the head gasket is at issue.

    I have a ’98 regular cab with the 4-cylinder, 5-speed manual, and only 75.5K miles. Yes, it’s hardly broken in yet — it’s been incredibly reliable.

    Still, while I might allow my sons to learn to drive on it (not personally applicable because mine are now over 30), if only to master the fine art of manual shifting, I’d never allow teenagers to use it on a daily basis because of the crash test ratings and lack of side airbags.

  • avatar

    One quart every two months is small enough to make locating the leak difficult. And three quarts of coolant (assuming you dilute it 50%) per year shouldn’t cost more than ten bucks or so. So I would make darn sure it’s not getting in the oil (look for milky colored oil on the dipstick) and if not just do nothing. If it gets worse then it should be easier to find; if it stays the same there is no real problem.

  • avatar

    Had a similar phantom coolant leak on my wife’s Jetta. Hers was due to VW” cheap plastic-engineering they use everywhere. The leak got pretty bad, but the oil looked good, the car never smoked, and no drops could be found on the ground. The Coolant would leak with the engine hot, puddle up on the transaxle, and burn off.

    I’m a mechanic, but I’m not familiar with your application. Coolant pressure testers works sometimes, although it’s been a crapshoot for me to find an actual leak with them. The best thing to do is to know the engine well and trace down every hose connection and around the water pump for any sign of wetness.

  • avatar
    Educator(of teachers)Dan

    B&B let us bow our heads and pray for Newsom. Blown h*** g****** are truly a scourge from Satan. (Just ask my Uncle Tim about his Cutlass Convertible with the 3.4 DOHC engine.)

  • avatar
    DC Bruce

    H***g****T — one of the many things that failed early on my 1980 Audi 5000 diesel. Look for milky oil or “steam” in the exhaust immediately upon startup.

    I would guess that a coolant leak that you smell comes from an external source, not a failing gasket. The dye sounds like a way to go, assuming the first two “tests” I mentioned are negative.

  • avatar

    Thanks for all of the great suggestions. To clarify a few points:

    1. It is the 3.0 V-6 and the right hand side of the engine is covered by the throttle body. I can’t even find the spark plugs on that side so the head gasket must be a ton of labor.

    2. The truck has endured several dents and dings from the daughter’s training. I want to the son to learn on the truck because it is a stick-shift. I agree that it is not the best in crash tests and the daughter went off to college in a Mazda 3 with a full complement of air bags.

    3. If the truck can survive the son I will keep it a long time as a garden/trash/lumber mover, (I wish it got better mileage though).

    4. Water pump was replaced with the timing belt at 90K. Inside heater core was replaced at around 60K due to A/C problem.

    5. I sent this question to Sajeev about a month ago and now I have a noisy lifter. I have tried a Gumout product and Marvel Mystery Oil with no results. Any suggestions on the new noise?

    Thanks for your help.


    • 0 avatar

      It’s actually 3.3L

      Are the lifters noisy just at start-up or all the time? Mine rattle like crazy for a few moments esp. on cold starts and have since around 45K miles. From what I’ve heard it’s pretty much the nature of the beast and replacing them is a temporary fix at best. I’ve been told to not worry about it if the noise goes away within a few seconds of starting.

    • 0 avatar
      Kevin Kluttz

      It’s more than likely a 3.3 litre. I had a 99 SE V6 and it looked like a bitch to get to anything under the hood. Ate me out of house and home (16.5 mpg no matter how or where I drove) and I traded it after 60000 flawless miles in 2 years. Nice big little truck.

  • avatar


  • avatar
    Ian Anderson

    Yep, do like Sajeev said and do the dye test, it should tell you in plain sight what the problem is (well, plain sight with a black light). I don’t know about the Nissan V6 in your truck but it could be a small coolant hose that you can’t see, possibly under the intake manifold. Speaking of the manifold it could also be its gasket, which isn’t as bad as a head gasket job, but on a V6 (let alone a cammer V6) it’s almost just as bad.

    If you want to do a quick test, let the truck cool down and pull the rad cap. If the underside of the cap has an oily/black residue on it, you’re probably looking at a BHG. Or run it down to an inspection/emissions shop, most (at least around here) will do a test using the sniffer that they use for e-testing <1995 vehicles (if they still have one). If it shows any combustion gases in the coolant it's also safe to say BHG.

  • avatar

    I had a Turbo Dodge that had a pinhole leak from a turbo coolant return line, we didn’t find the leak until after my wife overheated the car and ruined the head gasket. Without the dye test to verify, I think leak, not head gaskets. As for the lifter? Time for a LSx swap.

  • avatar

    Do you get steam on the windshield using the defroster>? Might be the heater core. It has a vent to the underside and that might be where you are getting a little leakage.

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