Piston Slap: The Last Frontier, The Dreaded H*** G****t?

Newsom writes:

Sajeev,

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 sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry.