Coolant pressure cap not replaced after service.

[Al94]

So, today I needed to top up my screen washer fluid.

Vehicle had a two year service on 6 September 2023 by Hyundai main dealer and has had little use since then (1300 miles) due to holidays and major orthopaedic surgery which kept me off the road. As soon as I opened the bonnet today to refill the screen washers I noticed that something was amiss, namely the pressure cap on the coolant reservoir was missing. I then spotted it sitting on the plastic scuttle below the windscreen behind the nearside suspension strut obviously removed and not replaced at the service.

Fortunately and surprisingly the coolant level appears ok and minimal sign of any splatter. Any opinion on the likely effect of this?

I will be on to the dealers first thing on Monday to complain about this shoddy error!

[GrumpyDad]

Obligatory: You likely won't have anything to worry about if you never saw any indications of overheating. But for the sake of a detailed answer, a few bad case scenarios to be aware of (but to be clear - the following seem very unlikely based on your description).

The majority of issues that would be likely to arise are generally caused by a loss of coolant (which can then lead to over-heating, which could lead to a head gasket failure), or boiling coolant being splashed onto electrical components, leading to component damage.

The coolant level being reasonable hopefully means that you have avoided over-heating. You've said that you have observed minimal splatter, so hopefully that also means that you will have avoided potential electrical issues; but perhaps just a careful visual inspection of sensors and wiring in the engine bay would be prudent.

The one potentially serious issue that remains, is whether there has been any (additional) water ingress into your coolant system. This has the potential to cause corrosion, leading to a premature failure in the coolant system (if it is ignored). Minimal driving hopefully means that isn't an issue either. Although, if the main dealer accepts that their mechanic/technician left the pressure cap off, maybe you could ask them to check coolant quality; and ask them to drain and replace the coolant if it is now out of spec. (But if we're honest, you'll probably have an uphill struggle getting anybody to admit it is even possible that the mechanic/technician left the cap off).

If you cannot get the dealer's service centre to give you a free coolant test (or don't want to drive the car out to them just for a quick test), you will find coolant quality testers are inexpensive; and honestly every driver should strongly consider having one in their toolkit (same with a brake fluid tester for the appropriate fluid, and a combustion gas leak tester kit).

I just double checked in my owner's manual, and it stated that the NX4 series Tucson has an aluminium radiator and requires an ethylene glycol based coolant. So I will defer to Auto Express for an appropriate recommendation. In July 2022 they did a group test for quality testers. Their top pick was the Draper 35807, which happens to be an ethylene glycol tester, which should be available for between £10 and £15 at your local motor-factors. It is available directly through the Draper Tools website (at time of writing it is listed at £15.35 plus VAT... No idea why it is so expensive direct) https://www.drapertools.com/search.php? ... uery=35807 or through the Draper Store on Amazon (at time of writing, it is priced at £11.16 including VAT) https://amzn.to/47u8sNK

[Al94]

Contacted the dealers this morning and emailed photos. As part of the service the coolant was replaced, an outstanding recall due to concerns about quality. They admit it is obvious the mechanic omitted to replace the cap and said they would check who it was and deal with it. They want the car in this week for a health check. I doubt any harm has been done but will have the check done in case any related warranty issues should arise.

[GrumpyDad]

That's a very impressive result. Clearly, the years have done a number on my cynicism. Good that they want to do a check, but I would say you are right that it is very unlikely any harm has been done.