Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[NickA]

I've a couple of problem with my 'mega that I'd appreciate some advice on before I start buying parts...

It's been running at 80 deg on the temp guage ever since the colder weather's been with us ( a month or two). If I switch the air con to eco which stops the two front fans from running, the temp will rise a bit, but it never gets to middle gauge. MPG's down by about 5 mpg as well. I reckon it's the thermostat not closing properly so that's due a change.

Also the more annoying fault is it won't start when the engine's warm. It just turns and turns over but never catches. If it's cold or it's been standing for just a few minutes it starts. So if I stop its got to be a quick 10 mins or a few hours.  Had to call the AA out last night as I'd flattened the battery trying to start the car. By the time he came the car had cool in the -2 temp and it fired up first time with jump leads. He thinks its could be the crank sensor so that's also on the list to change.

Anyone else have any other good ideas or suggestions?

It's a 2002 2.6 with 110,000 miles on it.

Thanks
Nick

[Kevin Wood]

Regarding the temperature, later V6s seem to run cooler than early ones. Mine only runs at about an indicated 80-85 or so once fully warmed up, unless in traffic with climate off, in which case it rises to 90-92 or so before the radiator fans limit it.

The thermostat is not an easy job so make sure it's definately knackered before tackling it. Try letting the engine idle from cold whilst feeling the temperature of the top radiator hose. If it warms up gradually with the engine it could be a thermostat problem but if it stays cold or thereabouts until the engine has reached operating temperature and then suddenly gets very hot, I'd say it's fine. Dashboard gauges are only an indication and generally not that accurate.

Regarding the fuel consumption I wouldn't say that it's unusual to drop a few MPG in this weather. I wouldn't expect as much as 5 MPG but if you do lots of relatively short trips maybe that's not unexpected.

Regarding failure to start from hot, I'd say it might well be your crank sensor on the way out. If you can get the codes read from the engine ECU (you need a code reader for a 2.6) I reckon you'll see code 335. I had exactly the same symptoms when mine went.

When refitting the sensor, look at the HOWTO on here for information on how to route the cable so the new sensor is more reliable. It's not a difficult job.

Cheers,

Kevin

[cem_devecioglu]

Agreed Kevin..But Crank sensor is critical..Will let you in the middle of traffic..

[Kevin Wood]

Agreed Kevin..But Crank sensor is critical..Will let you in the middle of traffic..

Agreed. Fortunately I diagnosed mine after only a couple of difficult starts and replaced it before it let me down badly. I'd get the codes read ASAP and, if it's a 335, replace the crank sensor.

Kevin

[NickA]

Agreed Kevin..But Crank sensor is critical..Will let you in the middle of traffic..

Agreed. Fortunately I diagnosed mine after only a couple of difficult starts and replaced it before it let me down badly. I'd get the codes read ASAP and, if it's a 335, replace the crank sensor.

Kevin

Does it store the codes after a failure to start or do they clear after it starts?  I've just driven 150 miles back from a clients, without a problem.  Park it on the drive and try it start it after 5 mins it starts fine. Just tried again after 30 mins and it wont start. Engine temp is showing 75. Once it's dropped to the gauge stop I know it'll start. I don't want to pay the Vox dealer to check the codes so I'm tempted just to change the sensor anyway. Having read the How To it doesn't look too difficult.

[NickA]

The thermostat is not an easy job so make sure it's definately knackered before tackling it. Try letting the engine idle from cold whilst feeling the temperature of the top radiator hose. If it warms up gradually with the engine it could be a thermostat problem but if it stays cold or thereabouts until the engine has reached operating temperature and then suddenly gets very hot, I'd say it's fine. Dashboard gauges are only an indication and generally not that accurate.

Top hose warms gradually so I guess that does point to the 'stat. If it was easy I'd do it tomorrow but reading the haynes manual there seems to be a lot of part to remove to get to it. I'll worry about this once I've fixed the starting problem. Can't see a how to for this on the forum, not a common problem?

[Kevin Wood]

Here's the crank sensor HOWTO: http://www.omegaowners.com/forum/YaBB.pl?num=1174321688

Crank sensor is about 40 odd quid on trade club. Sounds 95% likely that's your problem but maybe there's a member in your area with a cheapo tech 2 who can verify.

Had a feeling there was a thermostat replacement one but it appears not. It's not a common problem on the V6, thankfully.
The thermostat is in the Vee towards the front of the engine and a solid pipe connects it to the nearside where it joins the top radiator hose. Access to the bolt securing this pipe to the nearside cylinder head is the biggest issue.

Not done it myself but I'm sure someone who has will be along with some further words of advice.

Kevin

[Big_Roger]

I have just finished changing the thermostat on my 3.2 L V6

I combined the job with a cambelt and water pump change which made it easier, but the thermostat is still a very awkward job to replace.

The bolt holding the transfer pipe into the top of the thermostat is a sod to get out, and even more so to get in again. Once you have loosened the bolt with a torx socket its easier to get out with a 10 mm flexi head ratcheting ring, and same to put back. (no one seems to make torx ring spanners !!)
To take the transfer pipe out of the thermostat housing you have to turn it anti clock with pipe grips to get the transfer pipe fixing bracket from behing the oil dipstick pipe before you can pull it out.
Make sure you leave the engine lifting lug in place as it is part of the spacer to get the transfer pipe in the correct distance. The transfer pipe bracket sandwiches the engine lifting lug and the dipstick pipe holding bracket  between it and the cylinder head

When you buy the thermostat, make sure to get the new sealing ring, it dosn't come with the thermostat, and also get two new seal rings for the transfer pipe, it's too big a job to risk any leaks.
You wil need to use smear of grease on the end of the pipe and seal rings to ease it back in, and to stick the thermostat seal ring in the groove on the housing. I use silicone grease for all this.

 It is fiddly getting the thermostat housing back in place, but whatever you do, make absolutely sure the seal ring hasn't come out of the groove before you tighten down. use cranked inspection mirror & torch etc. don't tighten it right down untill you have then got the transfer pipe in place.
The front bolt goes right through to the water jacket so put a smear of jointing compound on the threads of the bolt to make sure of no leak. If there is any water in the rear bolt tapped hole in the top of the crankcase, soak it out, you don't want to chance a crack due to hydraulic pressure when you screw the bolt in.

Patience is the best tool for this job.

Roger

[NickA]

Quick update, changed the crank sensor today. Apparently there are two possible type for my 2002 v6, GM or Bosch. Mine had the cheaper Bosch one. Swapped it over and the 'mega starts quicker and idles much much more smoothly. So far it's started every time I've tried so fingers crossed it's fixed!

[NickA]

I have just finished changing the thermostat on my 3.2 L V6

I combined the job with a cambelt and water pump change which made it easier, but the thermostat is still a very awkward job to replace.

The bolt holding the transfer pipe into the top of the thermostat is a sod to get out, and even more so to get in again. Once you have loosened the bolt with a torx socket its easier to get out with a 10 mm flexi head ratcheting ring, and same to put back. (no one seems to make torx ring spanners !!)
To take the transfer pipe out of the thermostat housing you have to turn it anti clock with pipe grips to get the transfer pipe fixing bracket from behing the oil dipstick pipe before you can pull it out.
Make sure you leave the engine lifting lug in place as it is part of the spacer to get the transfer pipe in the correct distance. The transfer pipe bracket sandwiches the engine lifting lug and the dipstick pipe holding bracket  between it and the cylinder head

When you buy the thermostat, make sure to get the new sealing ring, it dosn't come with the thermostat, and also get two new seal rings for the transfer pipe, it's too big a job to risk any leaks.
You wil need to use smear of grease on the end of the pipe and seal rings to ease it back in, and to stick the thermostat seal ring in the groove on the housing. I use silicone grease for all this.

 It is fiddly getting the thermostat housing back in place, but whatever you do, make absolutely sure the seal ring hasn't come out of the groove before you tighten down. use cranked inspection mirror & torch etc. don't tighten it right down untill you have then got the transfer pipe in place.
The front bolt goes right through to the water jacket so put a smear of jointing compound on the threads of the bolt to make sure of no leak. If there is any water in the rear bolt tapped hole in the top of the crankcase, soak it out, you don't want to chance a crack due to hydraulic pressure when you screw the bolt in.

Patience is the best tool for this job.

Roger

Mine's also due a Cambelt change, it was last done 2 year/40K ish ago. If there's a lot of crossover with the thermostat I'll probably also combine the jobs.

[alanfp]

Re: Kevin's advice about the thermostat to "make sure it's definitely knackered before tackling it" - I'd suggest a few swift blows with a club hammer; that should make sure  

Sorry, old joke, but I have to take my opportunies where they arise!

[TheBoy]

Regarding the temperature, later V6s seem to run cooler than early ones.

The needle is in the same place on the gauge - they adjusted the gauge markings to go from 90 - 100 to 80 - 100