Piston Slap: That Slow TSI Coolant Burn?

Sajeev Mehta
by Sajeev Mehta
piston slap that slow tsi coolant burn
Jonathan writes:Sajeev,Our 2016 Passat (turbocharged 1.8-liter four-cylinder) appears to be losing coolant at the rate of a quart per year. We are driving the car only 5,500 miles per year in Chicago, so the coolant system isn’t under a whole lot of loan most of the year. I don’t have any spots on the garage floor under the engine, and the dealership checked for leaks and couldn’t find any.The dealership did say that turbo engines are expected to eat some oil and coolant, and that there is nothing to worry about. Is that really a thing? I am very skeptical, but I know very little about maintaining engines with a turbo.What say you?Sajeev answers:As mentioned previously, many a modern mill is cool with oil consumption. Perhaps tolerances on your turbo’s internal water cooling and oil cooling/lubrication- infused bearings are such that, in theory, the VW EA888 motor and its BorgWarner K03 turbo could burn coolant even at such a young age. But there’s another reason why…The EA888’s exhaust manifold (that feeds the turbo) is internal to the engine! More to the point, the engine’s coolant passages snake around the exhaust manifold runners, then spit coolant in (and suck it out) of the turbocharger. Engineering Explained covers this cooling system (starting at 4:20), so we can extrapolate if/how this causes coolant loss.Can this integrated exhaust manifolding mean coolant is under more heat/pressure to perform? And perhaps does it creep past seals and burn up at those stupidly fast and hot turbocharger bearings?But I wouldn’t worry about this slow TSI Coolant Burn, because there ain’t much you can do about it. Do whatever maintenance the owner’s manual says ( or not). If your Passat consumes a quart of coolant monthly, if the warranty expires, I am sure a rebuilt turbo (built in your specific housing) won’t be too painful on the wallet, since there are standardized guts within that case. And mercifully, that TSI designed case isn’t that unique in VW Land.What say you, Best and Brightest?[Image: Volkswagen]Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.
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  • Wadenelson Wadenelson on Jun 12, 2018

    Both Chevy Vegas and some Jaguar E-types perpetually lost coolant due to a too-small OEM overflow reservoir. It would overflow a tiny amount after a hot shutdown somewhere far from home, and owners often wouldn't notice the wet spot. I'd suggest checking your overflow bottle and hoses for cracks, pinholes for a "mystery leak" like yours and note if the level goes all the way to the top after a good heat soak after a hard run.

  • Gearhead77 Gearhead77 on Jun 19, 2018

    My 2017 Golf 1.8 didnt use any oil or coolant in the same amount of miles from new. It did say in the owners manual that “driven in a certain manner, some oil use is expected” and gave a figure that escapes me now.

  • Tassos What was the last time we had any good news from Ford? (or GM for that matter?)The last one was probably when Alan Mulally was CEO. Were you even born back then?Fields was a total disaster, then they go hire this clown from Toyota's PR department, the current Ford CEO, Fart-ley or something.He claims to be an auto enthusiast too (unlike Mary Barra who is even worse, but of course always forgiven, as she is the proud owner of a set of female genitals.
  • Tassos I know some would want to own a collectible Mustang. (sure as hell not me. This crappy 'secretary's car' (that was exactly its intended buying demo) was as sophisticated (transl. : CRUDE) as the FLintstone's mobile. Solid Real Axle? Are you effing kidding me?There is a huge number of these around, so they are neither expensive nor valuable.WHen it came out, it was $2,000 or so new. A colleague bought a recent one with the stupid Ecoboost which also promised good fuel economy. He drives a hard bargain and spends time shopping and I remember he paid $37k ( the fool only bought domestic crap, but luckily he is good with his hands and can fix lots of stuff on them).He told me that the alleged fuel economy is obtained only if you drive it like a VERY old lady. WHich defeats the purpose, of course, you might as well buy a used Toyota Yaris (not even a Corolla).
  • MRF 95 T-Bird Back when the Corolla consisted of a wide range of body styles. This wagon, both four door and two door sedans, a shooting brake like three door hatch as well as a sports coupe hatchback. All of which were on the popular cars on the road where I resided.
  • Wjtinfwb Jeez... I've got 3 Ford's and have been a defender due to my overall good experiences but this is getting hard to defend. Thinking the product durability testing that used to take months to rack up 100k miles or more is being replaced with computer simulations that just aren't causing these real-world issues to pop up. More time at the proving ground please...
  • Wjtinfwb Looks like Mazda put more effort into sprucing up a moribund product than Chevy did with the soon to be euthanized '24 Camaro.