What are the most common Mazda RX-7 problems?

According to Au7o's analysis of 730+ owner reports, the 1991-1991 Mazda RX-7 has 2 documented issues. The most frequently reported are: Rotary Apex Seal Failure, Overheating and Coolant System Weakness. Of these, 2 are rated critical and should be addressed promptly.

Is the Mazda RX-7 reliable?

The 1991-1991 Mazda RX-7 has 2 known issues documented across 730+ owner reports. 2 issues are rated critical: Rotary Apex Seal Failure and Overheating and Coolant System Weakness. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Mazda RX-7 problems?

Repair costs for known Mazda RX-7 issues range from $300 to $5,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Rotary Apex Seal Failure, typically costs $2,000-$5,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

1991 Mazda RX-7 Problems: 2 Issues Every Owner Should Know

1991 model year · 730+ owner reports · Updated April 2026

Share:@au7o.io

According to Au7o's analysis of 730+ owner reports, the 1991 Mazda RX-7 has 2 documented known issues, with 2 rated critical. The most serious are Rotary Apex Seal Failure ($2,000-$5,000 repair) and Overheating and Coolant System Weakness ($300-$800 repair). The most commonly reported issue is Rotary Apex Seal Failure with 450 owner reports. Across all issues, repair costs range from $300 to $5,000. DIY maintenance guides at au7o.io.

All 2 Known Issues

Filter:

Community Reported

450 owners

On the 1990-1995 Mazda RX-7 13B, apex seals on the 13B rotary engine wear and fail, causing compression loss and poor running. Turbo models run hotter and accelerate wear. Requires engine rebuild to replace.

Common Symptoms

Loss of power
Hard hot starting
Low compression on rotary compression test
Excessive exhaust smoke
Poor fuel economy
Flooding on restart

How to Fix

Rebuild rotary engine with new apex seals, corner seals, and side seals. Use OEM Mazda seals for reliability. Premix 2-stroke oil in fuel (1 oz per gallon) to extend seal life.

What Owners Are Using

Parts and tips from 450+ owners who fixed this issue

TipPremix 2-stroke oil in your fuel at 1 oz per gallon — it lubricates apex seals and extends engine life significantly
TipNever lug the engine at low RPM — rotary engines need to rev to maintain proper seal contact
UpgradeBluetooth OBD-II scanner for reading engine codes and monitoring live data (BlueDriver Bluetooth OBD2 Diagnostic Scan Tool)
View on Amazon
UpgradeQuality synthetic oil and filter combo for engine maintenance (Mobil 1 Full Synthetic Oil and Filter Bundle)
View on Amazon

Typical repair cost:$2,000 - $5,000

Research This Issue

450+ owners have reported this issue

Google Reddit YouTube NHTSA

Community Reported

Low Confidence450 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

280 owners

On the 1990-1995 Mazda RX-7 13B-REW, rotary engines generate extreme heat and the cooling system is barely adequate, especially on turbo models. Radiator, thermostat, and water pump failures cause rapid overheating that quickly damages apex seals.

Common Symptoms

Temperature gauge climbing
Coolant boilover
Steam from engine bay
Temperature spikes in traffic
Fan not engaging

How to Fix

Upgrade to aluminum radiator. Replace thermostat and water pump proactively. Monitor coolant temperature closely. Never drive with high temps — rotary engines suffer immediate seal damage.

What Owners Are Using

Parts and tips from 280+ owners who fixed this issue

TipUpgrade to a Koyo or Mishimoto aluminum radiator — the OEM radiator is marginal for cooling needs
UpgradeDenso OE-quality radiator — direct fit replacement (Denso Radiator)
View on Amazon
UpgradeMishimoto performance aluminum radiator for improved cooling (Mishimoto Aluminum Radiator)
View on Amazon
UpgradeGates water pump — OE-quality replacement with gasket (Gates Water Pump)
View on Amazon
UpgradeGMB water pump — reliable OEM alternative (GMB Water Pump)
View on Amazon
UpgradeStant thermostat — OE-spec temperature control (Stant Thermostat)
View on Amazon
UpgradeGates thermostat with housing for complete replacement (Gates Thermostat)
View on Amazon

Typical repair cost:$300 - $800

Research This Issue

280+ owners have reported this issue

Google Reddit YouTube NHTSA

Community Reported

Low Confidence280 reportsLast reported by owners Mar 2026Reviewed Mar 2026

1991 Mazda RX-7 Problems: 2 Issues Every Owner Should Know

All 2 Known Issues

1990-1995 Mazda RX-7: Rotary Apex Seal Failure#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

1990-1995 Mazda RX-7: Overheating and Coolant System Weakness#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

Other Mazda Models

Frequently Asked Questions

What are the most common Mazda RX-7 problems?

Is the Mazda RX-7 reliable?

How much does it cost to fix common Mazda RX-7 problems?

What is the 1990-1995 Mazda RX-7 Rotary Apex Seal Failure?

What is the 1990-1995 Mazda RX-7 Overheating and Coolant System Weakness?