Mazda Rotary Club

General => General Technical => Topic started by: scud on August 16, 2005, 01:04:21 AM

Title: Wont start when hot
Post by: scud on August 16, 2005, 01:04:21 AM
What does it acually mean when a rx7 wont start when the engines hot.

Im looking at a car but the ad says " the car will start normal,run normal but it wont restart off the key when the engine is hot.
Is this a big problem ?

Thanks
Scud
Title: Wont start when hot
Post by: Brett on August 16, 2005, 08:31:10 AM
Could be leaking injectors or poor compression, or both.
Title: Wont start when hot
Post by: grinder on August 16, 2005, 09:40:53 AM
its a big enough problem to walk away from it - unless its super cheap
Title: Wont start when hot
Post by: Warthog on August 16, 2005, 01:45:56 PM
It\'s a rebuild job. Just had my engine done, it had the same problem. Side seals etc had gone. Don\'t buy it unless it\'s dirt cheap.HTH. :wave
Title: Wont start when hot
Post by: iaint on August 16, 2005, 02:46:00 PM
Quote from: scudWhat does it acually mean when a rx7 wont start when the engines hot.

Im looking at a car but the ad says " the car will start normal,run normal but it wont restart off the key when the engine is hot.
Is this a big problem ?

Thanks
Scud

It is, as posted, almost certainly the sign of a very tired engine.  Basically, the compression is low (i.e. the seals and housings are badly worn).  When cold the oil is more viscous (less runny) than when hot and therefore has compression when cold but not when hot.

Once the engine is running it generally keeps going because (i think) the gyroscopic forces help the rotor tips make a decent seal.

Walk away if it\'s above 4k.  The rebuild will be a minimum of 3k realistically and likely to be in the 3-4k region.  Car after will be worth (if standard) up to 8-8.5k.  Do your sums and take your choice!

Iain
Title: Wont start when hot
Post by: scud on August 16, 2005, 10:58:51 PM
Thanks for advice guys, gotta give it to ya you lot know your stuff.

Cheers
Scud
Title: Wont start when hot
Post by: Carl on August 16, 2005, 11:26:34 PM
once the engine is running the gas pressure from combustion helps to make a good seal by getting behind them and forcing them to do so.
When the engine is hot the seals and springs that are tired and worn don\'t give such a good seal due to everything expanding and bigger clearances opening up.
So the engine does as everyone has said in all likelyhood need a rebuild.
Regards
Carl