Why is my Porsche 944 overheating or clicking after new spark plugs?

Short answer: A 944 running hot usually has old hoses, a weak cap or a leak; a pressure test finds it. If it started clicking right after new plugs, a plug or its connector is likely loose or damaged.

Symptom: The temperature gauge climbs toward red, or a ticking or snapping noise started right after a plug change.

What to check first

1. With the engine cool, check coolant level and look for leaks.
2. Squeeze the hoses for soft or collapsed spots.
3. Replace or test the cap.
4. Have the cooling system pressure tested.
5. After a plug job, check each plug is tight and each connector is fully seated and not cracked.

Likely causes

1. Collapsed or weak coolant hoses. Old hoses can collapse under suction and block coolant flow.
2. Bad radiator or expansion tank cap. The cap holds pressure so coolant doesn't boil. A weak cap lets it boil over sooner.
3. Coolant leak. A pressure test pumps the cooling system up to find leaks you can't see.
4. Loose or damaged spark plug or plug connector. After a plug change, a plug not tightened properly or a cracked boot or connector can let spark jump out and make a ticking or snapping noise.

What it usually costs

Owners didn't post prices. Caps and hoses are modest parts; a pressure test is a common shop service. Get a quote from a Porsche specialist.

Is it safe to keep driving?

Don't drive an engine that's running near red. It can warp the head. A plug that's arcing can cause misfires and damage the coil or plug threads, so fix it before driving hard.

DIY or shop?

Cap, hoses and plug checks are DIY. A pressure test needs a tester or a shop.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists 8 recalls for the 944 in these years. Two are fuel-line items: 85V039000 (1985, a fuel hose may be damaged where its end fitting was crimped, which could leak fuel) and 86V077000 (1986, part of the return fuel hose was left uncovered and can kink from engine heat). None is about overheating or spark plugs. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, a Porsche dealer fixes it for free.
• Plain words: NHTSA data for the 944 is limited, so owner experience carries most of the weight here.
• NHTSA complaints: 2 keyword-matched complaints for Porsche 944 1983–1991 (of 18 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-28; keywords: overheat, coolant, cool, temperature, radiator, water pump, spark, miss) (NHTSA returned no data for 2 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 1985 Porsche 944 with cooling problem on Car Talk, a 1985 944 owner saw the temperature gauge near red. Members said to check for collapsed hoses, replace the cap and have the cooling system pressure tested.
• In Click/Spark noise after changing spark plugs - 1990 Porsche 944 S2 on Car Talk, a 1990 944 S2 started clicking after new spark plugs. Members suspected a loose or damaged plug or connector, suggested stock-type plugs, and said to torque them to spec (they cited about 18-22 ft-lb).

Quick tip

If a noise started right after you changed plugs, go back to the plugs first.

Vehicle focus: Porsche 944, 1983-1991, including the S2.

Safety / mechanic note

Let the engine cool before opening the cooling system. Verify with a mechanic.