New(To Me) '90 740 With Bad Fuel Economy + Tick

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Acquired an eBay '90 740 NA one month ago for $1k on eBay. B230F engine with auto and 180k on the clock. No leaks but ran like [censored] and with hole in exhaust sounded great. Installed stock exhaust, plugs, wires, O2 sensor, K&N, and one AutoRX treatment. Runs 1000% better now but fuel economy is between 16-18mpg with 50/50 city/hwy. There's also a persistent and audible tick coming from the engine at a rate of perhaps 12 ticks/knocks per second. Is this normal?
 
and it's not the injectors?

Is your TCC locking up? Does overdrive work?
 
For the most part volvos are solid cars with great engines but you must make sure your timing belt is in good shape because if that belt breaks so does your engine in most cases
 
3m intake cleaning kit on woot right now.

Have you checked for any stored codes?

Cat replaced with exhaust?
 
It's rated 18/24. An O2 sensor failed in the rich position will kill mileage. Also the gas sitting in there awhike might do the same.
 
Can't find the 3M woot deal...

Originally Posted By: 05LGTLtd
3m intake cleaning kit on woot right now.

Have you checked for any stored codes?

Cat replaced with exhaust?
 
When did this car last have its "flame trap" serviced?" (PCV system). The flame trap is often neglected on Volvos. A plugged PCV system can cause problems. All the other suggestions were good. Are there any DTC fault codes. If yes, address them. If not, then the flame trap is a possibility if the PCV hoses are plugged up. There are good websites to purchase these from so you don't have to go to the dealership. Read up on the shop manual procedure. If the intake is also badly crudded up, you may want to pull it and clean it.

Give us more info on when the tick occurs (idle?, uphill?, low speed?, etc.).

Dr. Olds
 
Originally Posted By: gr8gatzby
Acquired an eBay '90 740 NA one month ago for $1k on eBay. B230F engine with auto and 180k on the clock. No leaks but ran like [censored] and with hole in exhaust sounded great. Installed stock exhaust, plugs, wires, O2 sensor, K&N, and one AutoRX treatment. Runs 1000% better now but fuel economy is between 16-18mpg with 50/50 city/hwy. There's also a persistent and audible tick coming from the engine at a rate of perhaps 12 ticks/knocks per second. Is this normal?


I thought it had the 16 valve engine? If so, that is a B234F (16 valve), not a B230F which is the 8 valve engine. You might want to double check that all of the parts that you installed are correct for a B234F. I know that the exhaust system for a 16v has some differences and they use the Bosch fuel injection while some 8 valve cars used the Regina/Bendix fuel injection. That system uses a different oxygen sensor which will physically fit a car with Bosch injection but is incorrect.

I would also replace the cap and rotor in case you haven't already with a quality replacement that has brass contacts.

Andrew S.
 
I agree with the O2 sensors. Did you change the catalytic converter? It could be plugged up. Spray some brake cleaner around the engine to check for vacuum leaks while it's running.
 
3M DIY Kit:- Amazon most likely has it at just over $20. You can also find 3M rebate form over the internet for $10. It is a screaming deal for just over $10 after rebate. I have three in my basement and I am still looking to purchase another one "just in case"!
 
If you're lucky the tick is a bad injector. That would explain both the tick and the mpg. Try to locate the source of the tick with a stethoscope.

Of course it could be a bad valve or lifter, which would be more expensive/involved to fix.
 
Generic advice. What do the plugs look like ? Does the oil smell gassy , Did gas run out of the vacuum hose for the fuel pressure regulator. If the 2 wire coolant temp sensor isnt brand new, replace it. If the distributor cap has brass contacts , clean them and scrape the carbon off the rotor tip. Be sure to clean the inside of the cap until it is shiny. This to remove any carbon tracking between terminals. If the O2 sensor, doesnt make a meter dither rapidly between .2 and .8 VDC replace it. Take the air filter out and see what it looks like. Knock it against your heel to get the dust out of it. If it has a noticeable skip, isolate the cylinder by pulling the plug wire or the injector plug. If the noise or the skip doesnt worsen, then you have found the location. We found it on my DIL's CRV with a compression test. A burnt exhaust valve was revealed
grin2.gif
 
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Check the exhaust gaskets for leaks, which occasionally masquerades as ticking on these. Be aware that some older Volvos can have very loud injectors. Other times, ticking on the redblocks is caused by normal valve train wear, which can be corrected by replacing some o-rings in the followers to restore zero lash. If so, I'd just live with the noise, until the next t-belt job.

A slight knocking when cold can also be a little piston slap, which is not unusual for these engines. It won't affect durability one bit.

The mileage seems within the range otherwise.

Good old school Volvo. Should run forever if taken care of. Just don't stack five cars on one like in the old TV ads. Good luck with it.
 
I had a loose spark plug that ticked. Took a good long while to figure it out. MPG went up also thanks to better compression.
 
I like BG 44K and Red Line Si-1 for an injector & top end cleaner. Nothing wrong with 3M either, if you can find it. I'd use at least one can since the car is new-to-you. You might also want to have the engine smoke-tested to find rotted/leaking vaccum hoses, which will affect MPG.

Re: Ticking. Might be fuel injectors. Mine's a 98 and they've always ticked louder than I thought appropriate. I've heard others of similar years that were very quiet, so I thought it a bit odd. I've also used BG's engine flush a time or two before an oil change. Be sure to drain the engine oil cooler if it has one.

Re: plugs. I only use OEM Volvo, copper core Bosch or NGK's.

Re: Intake. Remove the air hose to the throttle body, open the valve and shine a flashlight in there. If it's black and there's a persistent black ring around where the valve edge meets the aluminum, it needs cleaning with throttle body cleaner and a brass brush. I use either BG or Wurth TB cleaner because their cans will still spray upside down.

Keep us posted!
 
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