'95 850 turbo -- lag and oil weight

scots-man · Post by **scots-man** » 20 Jul 2007, 22:17

Recently I had to replace my engine because the previous one overheated, blew the head gasket and in turn fried the engine. I estimate it had about 190K as odometer stopped about 1 yr ago. The replacement engine has 85K miles and seems to be running fine. However, I now have turbo lag -- something I never really had before. The mechanic that replaced the engine told me that when he removed the blown engine there was water in the turbo and cat. He says he checked out the turbo before reinstalling and believes that the lag is due to back pressure from the "wet" honeycombs in the cat. As the cat dries the lag should decrease. Is this possible? If so how long should it take to dry?

Second issue -- he refilled crankcase with 20W50 stating that for older engines and especially whose that run hotter (due to turbo) this is better. He also added a qt of Lucas Oil Stabilizer. He argue that the heavier weight oil does not thin out and break down as much as the lighter and that the Lucas makes things more slippery, clings to cylinder walls and helps prevent dry starts. Volvo recommends 10W30 which I used faithfully in the previous engine. Are his arguments correct? Is it wise to use this heavier oil? Could this cause slow oil delivery to the turbo and cause the lag?

Thanks.

Post by **MadeInJapan** » 20 Jul 2007, 22:25

Get a different mechanic. I've never heard of anything he's saying and I've been around these cars for several years.

blackstarpower · Post by **blackstarpower** » 20 Jul 2007, 22:33

Lag comes from how big the turbo is.

scots-man · Post by **scots-man** » 20 Jul 2007, 22:41

that's what i thought. ok, so i dump the oil and go back to 10W30. any ideas on the lag? with old engine boost gauge would be at 12 o'clock when idling and maintaining constant speed until i pushed accel and then it would move into white.

replacement engine needle is at the center of the black portion of the gauge at idle and moves toward noon position while at constant speed.

Post by **MadeInJapan** » 21 Jul 2007, 04:25

Could be the timing on this engine is set slightly differently. I know that when I got my timing belt changed, my turbo spools up faster. Either that or you have a vacuum leak.

MadeInAmerica · Post by **MadeInAmerica** » 21 Jul 2007, 12:02

One more thing:
Dont be surprised if your cat is fried. I had a blown head gasket on a truck and the water going into the cat killed it. Just giving you a heads up on the possibility because at first we thought it was the carb and it wouldnt pass smog until the cat was changed.

Water entering into something 1200(thats what I think they can get up to) degrees can create problems.

Post by **JRL** » 21 Jul 2007, 12:51

scots-man wrote:that's what i thought. ok, so i dump the oil and go back to 10W30. any ideas on the lag? with old engine boost gauge would be at 12 o'clock when idling and maintaining constant speed until i pushed accel and then it would move into white.

replacement engine needle is at the center of the black portion of the gauge at idle and moves toward noon position while at constant speed.

If everything checks out, cat, etc, turn the wastegate rod by a turn and a half to two turns (clockwise, shorten it).
It may be way out of adjustment.
If you hit the sweet spot the turbo will boost quicker.
Please remember DO NOT OVER TIGHTEN IT.
It's tempting but don't do it for various reasons.
You never should add additives to a turbo motor so, as was said above, GET A NEW MECHANIC

scots-man · Post by **scots-man** » 21 Jul 2007, 13:17

this is great info thanks! btw, could some of this be related to a bad TPS? it threw a "high" code today and is running rich. pulled the TPS and will replace anyway.

Post by **JRL** » 21 Jul 2007, 13:47

scots-man wrote:this is great info thanks! btw, could some of this be related to a bad TPS? it threw a "high" code today and is running rich. pulled the TPS and will replace anyway.

Not really, different

KlubMarcus · Post by **KlubMarcus** » 21 Jul 2007, 14:30

MadeInJapan wrote:Get a different mechanic. I've never heard of anything he's saying and I've been around these cars for several years.

I agree. A heavy oil running through a turbo is bad news. Get oil with the specs the manufacturer recommends. Besides, with synthetic oils/blends nowadays there's not much worry with additives for high mileage anymore.