[FreddieLindsey]

Hi all,

I recently took a 1989 300SL into my local garage and they came back saying to me that the compression in the engine was running low. They said all cylinders should be at 190psi, but they are currently 175, 160, 160, 125, 140, 190 (1-6).

I'm going off in the car on a 3500 mile trip from the UK down to the South of France, across the Riviera, into Italy, up through Switzerland, up through Germany and France, and back into the UK.

I'm in a real quandary as to whether to take the car or not. Can anyone help?

Thanks!

 

[jaymaynard]

How is the car running?

 

[FreddieLindsey]

So the car isn't driven often. It's actually my Dad's car. He bought it as an investment and never drives it. I am madly in love with the car and think it's the most amazing thing for big tours.

I took the car 1500 miles last June in a week. It struggled to start the very first time we pulled her out of the garage. After that, she seemed to run great - hundreds of miles of smooth, beautiful driving. There has been the odd time (when it hasn't been driven for a while) when putting her into R from P causes the revs to drop so much that it stalls, but I haven't had this repeat itself.

The last time it was driven (more than 10 miles) was last November when I took it 300 miles to Wales and back. After that it was put in for service and then came back in April with the seals on the gearbox replaced as they were leaking.

To tell you the truth, I was a bit shocked by the news the garage gave me, and they were saying it was likely the piston rings and valve stems. Apparently there is some issue with the exhaust valve as well to do with cylinder 4.

 

[nobby]

Here's my advice.

DRIVE THE CAR.

The End.


If you do get a chance, get the RPMs up....up high.....drive it in second gear for a while.....by the end of your trip I'll bet the compression is better.

Why was your mechanic actually checking the compression?

How many kms on the engine?

 

[FreddieLindsey]

The car was 'being a bit lumpy on idle' and he said there was a cracked idle hose. It struggled to start the first time we started it when we went last year, but after that (apart from the one time I cut the ignition short) it started great.

They checked the compression after they changed the idle hose they said.


The first two days of the trip are a 700 mile journey down to Marmande.

It's got 71000 miles on the clock if I remember, so around 115000 km.

Had the engine mounts and subframe bushes changed whilst it's been in, rear shock absorbers.

 

[FreddieLindsey]

I tend to cruise in it most of the time (70-75 mph) as above that the aerial whistles and it pisses the girlfriend (and me) off.

I love giving it those short blips though taking it up to 6500rpm, sounds so great!

 

[Weather Man]

Do it. On that itinerary you will never be far from help if you need it. The car will be improved for it.

 

[JS5D]

Not really high mileage. Low compression over several cilinders could be: wear dt high miles or poor oil maintenance etc., stuck rings, poor valve setting or poor compression test procedure.

Poor compression will result in poor starting and misfire at idle, not really showstoppers on a road trip.

I agree that driving the car with some decent fresh oil and repeatimg the compression test by the book could resolve this issue

 

[RLT61]

I tend to cruise in it most of the time (70-75 mph) as above that the aerial whistles and it pisses the girlfriend (and me) off.

Get a wind blocker for the car if you don't have one. I can cruise at about 80mph+ and my wife, sitting in the passenger seat, still can carry on a phone conversation.

 

[Anovak]

DRIVE THE CAR.

While I understand your concerns, I'm in this camp too. When I drive my 280SL more often it seems to respond much better and progressively improves so that would be what I might expect. I also think the windscreen will be a huge improvement in terms of comfort when cruising at higher speeds, not to mention disposition of the "riders." Do you have something like AAA insurance over there? That may help to put your mind at ease should you require, however unlikely, roadside assistance. That said, in these days of cell phones and the ability to locate towing companies from practically anywhere, you may not even need anything else. How soon will you be leaving? Drive it as much as you can between now and your departure to get more of a feel for how it responds during this period. Have fun!

 

[FreddieLindsey]

I'm taking out RAC cover which will cover me for the whole trip. If the car breaks down and they can't fix it on the spot, it'll be taken to a local garage. If the local garage can't fix it within 6 hours or it's going to cost more than £1,000, it will be repatriated at some point between then and the end of my trip. I'll be given a hire car and we can continue our trip. I'll have to leave the car in the hands of the garage wherever that is, but then the RAC will take car of it coming home.

I am picking it up on the 28th and leaving on the 29th. Perhaps I'll go do a 100 miles in it on the 28th just to see how it's getting on.

I'm thinking that I've just got to have faith in her. It'll probably be fine, and I should go and enjoy the trip knowing I'm covered if I have a problem.

 

[Ears]

Seafoam per manu instructions... Get ready for what will look like Armageddon if you do

Seriously, seafoam can break/dissolve carbon deposits.
Now, on your trip... If the trip is the priority, then go for it! However, if getting to a particular place on a specific timetable is priority, opt for more reliable and trusted conveyance. something as simple as a rad hose can cause hours of "regret" when *SWMBO is fuming in the sun awaiting a tow.




(*She Who Must Be Obeyed, as your low post count indicates relatively new here)

 

[FreddieLindsey]

Seafoam per manu instructions... Get ready for what will look like Armageddon if you do

Seriously, seafoam can break/dissolve carbon deposits.
Now, on your trip... If the trip is the priority, then go for it! However, if getting to a particular place on a specific timetable is priority, opt for more reliable and trusted conveyance. something as simple as a rad hose can cause hours of "regret" when *SWMBO is fuming in the sun awaiting a tow.




(*She Who Must Be Obeyed, as your low post count indicates relatively new here)

This is a fuel additive right?

 

[Ears]

This is a fuel additive right?

The googler is your friend...
https://seafoamsales.com/

 

[okyoureabeast]

Assuming everything else in the car is up to spec (fresh oil change, new coolant, brakes pads, calipers, fluids, etc)

I would follow Nobby's advice and just drive it. Your gas over there is a higher octane which will help loosen up the gunk. Drive it hard and drive it fast!

 

[Ianwright40]

I would caution against Seafoam. Not so long back a chap with a 380 was posting here after using seafoam. His concern was smoke after using the seafoam. Some searches around the net will bring up other accounts of similar experiences... My thoughts are that it cleaned the crud out that was stopping the smoking. I would be more conservative and just use something like Techron or a few shots of STP. If the compression is going to clear up during the drive it will do so without buckets of cleaner. The cleaners available are considered essential or snake oil in various degrees depending on who you ask. There is very little empirical evidence that they work....

 

[jaymaynard]

I wouldn't worry about low compression unless the car is having actual problems that are evident to the driver without needing special equipment. If the car drives fine, drive it and don't worry...especially since your RAC coverage sounds like it'll take care of any problems that might crop up.

 

[Nate D. Rector]

rent a bicycle instead,it would be much more fun,let your motor be rebuilt.