Tech Tip: Pleasant Surprise - Plugging Nissan Head Leak

Tech Tip: Pleasant Surprise – Plugging Nissan Head Leak

Any technician who has worked extensively with Asian-made vehicles has more than a casual acquaintance with head gasket replacements. It comes as no surprise that when you put an aluminum head on a cast iron block, the different expansion rates of the two metals will eventually weaken the head gasket.

Any technician who has worked extensively with Asian-made vehicles has more than a casual acquaintance with head gasket replacements. It comes as no surprise that when you put an aluminum head on a cast iron block, the different expansion rates of the two metals will eventually weaken the head gasket.

With that fact in mind, it is amazing how many miles these vehicles can log before the head gasket has to be replaced. On the other hand, some vehicles can experience a leaking head gasket with only 30,000 miles on the odometer. So, when water is leaking out from behind a timing belt cover, no matter what the mileage, what is the first thing that comes to your mind? It must be a leaking head gasket. But maybe this time, it’s not.

Such is the case with 1990 to 1995 Nissan Pathfinders or trucks equipped with a VG30E engine. These vehicles can develop a coolant leak that runs down behind the timing belt covers and appears to be coming from the head gasket(s). But my friends, you want to be sure. It’s a good idea to spend the time to remove the timing belt covers to check out this problem completely.

Use the following procedure for identifying and repairing the source of the coolant leak:

1. Drain the coolant and remove the following components: cooling fan, all drive belts, water pump pulley, distributor protector, A/C compressor drive belt idler bracket, fresh air intake tube for rocker cover, water hose from thermostat housing, crankshaft pulley bolt and pulley.

2. Remove the front timing belt covers, timing belt, upper camshaft timing gears and the rear belt cover/dust shield. Prior to removing the timing belt, manually rotate the engine so that #1 cylinder is on its compression stroke and align timing marks (this will ease re-assembly).

3. Inspect the threaded blind plugs located directly below each camshaft. If coolant, corrosion or a powdery residue is noticeable around the outside edges of either blind plug, use a suitable Hex wrench and remove the offending blind plug from the cylinder head.
NOTE: It is not necessary to remove and disassemble the cylinder head for this repair.

4. Clean off all traces of coolant, sealer and residue from the blind plug and cylinder head threads.

5. Apply Teflon tape or a suitable pipe thread sealer to the threads of the blind plug.

6. Re-install the blind plug into the cylinder head. Torque to 50 ft. lb. +/- 2 ft. lb.

7. Re-install the components mentioned in steps one and two and add fresh coolant.
NOTE: Make sure to bleed all the air from the cooling system before a test drive.

The vehicle owner knew what it would have cost to replace one or both of the head gaskets. You told them, right? In this case, the labor charge for the repair will be only slightly higher than the diagnostic time. This is the kind of pleasant surprise that customers remember for years. Not only will they be happy to pay this bill, the great "word of mouth advertising" they generate will be priceless.

Written by ALLDATA Technical Editor, Rich Diegle. Rich is an Advanced Engine Performance Certified and ASE Master Technician with an Associate of Arts degree in automotive technology and 22 years of dealership and independent shop experience.

Courtesy of ALLDATA.

For additional information, visit www.alldata.com.

You May Also Like

Autel’s CSMS Achieves OCPP 2.0.1 Certification

The Charging Station Management System obtained the certification from the Open Charge Alliance.

Autel Energy announced that its Charging Station Management System (CSMS) has obtained the OCPP 2.0.1 Certification from the Open Charge Alliance (OCA).

OCPP 2.0.1, the latest version of Open Charge Point Protocol (OCPP) released by OCA in 2020, is the globally recognized standard for effective communication between charging stations and charging station management software, the company said. The protocol provides advanced smart charging capabilities and enhanced control features for utilities, Charge Point Operators (CPO), and EV owners. To date, only 14 companies worldwide have achieved this esteemed certification, Autel Energy said.

Tool Time Podcast: Lumileds

Nadine and Eric sit down with Lumileds’ Aubry Baugh to discuss all the professional lighting solutions the company has to offer.

Cummins, Daimler Truck and PACCAR Form Joint Venture

The completed joint venture is now known as Amplify Cell Technologies.

Bosch Announces 87 Aftermarket Parts Released in June

The new part numbers include 22 wiper part numbers, 35 rotating machines, 20 sensors, six spark plugs and more.

Modine Helps Fortify Zero-Emission Bus Fleet in Wisconsin

Racine transit system zero-emission buses are equipped with Modine EVantage to increase longevity and range.

Other Posts

TEXA Runs Car Diagnostic Tool Promotion

The promotion is active from June 1 through August 31.

Babcox Media Appoints Director of Strategic Partnerships

Tom Pecka will oversee the development and execution of strategic media partnerships and sponsorships, as well as enhance media activations across the company’s diverse media channels.

Please Take Our Brakes/Rotating Electrical Survey

By entering, you’ll have a chance to win a $100 gift card or one of 10 $25 gift cards!

Autel Approved for Nissan Central Gateway Access

This Nissan gateway access is available now on Autel MaxiSYS Ultra, MS919, MS909, MS906PRO, and MS906PRO-TS, and the remaining Autel tablets by May 30.