Mercedes

Have Mercedes questions? Ask a mechanic for answers ASAP

Ask an Expert,
Get an Answer ASAP!

I have a 1990 300SL that takes a time to start when its

Customer Question
I have a 1990...

I have a 1990 300SL that takes a long time to start when its cold. I have to press the foot feed down to prime it. once it starts it takes 5 minutes at idle to warm up then its runs fine. The mercedes mechanic said it needed a Cold Start Valve. $700 later. That did not fix it. Next they said it needed a Fuel Pressure Regulator. $500 later that did not fix it. Now they think its a vacuum leak and the need 6 hours of labor to take the manifold off to inspect it and no guarantee that will fix it. Where do I stop the bleeding. The car is very nice looking but has 150,000 miles. I paid $6000 for it and have put $2000 in it. When do I give up and sell it for salvage. Any ideas on what I should do?

Mechanic's Assistant: How many miles are on the vehicle? And when was it last serviced?

150,000 miles and seviced 200 miles ago

Mechanic's Assistant: Are you fixing your 300SL yourself? What have you tried so far?

Have you not read what I typed?

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

No just let me know please

Submitted: 5 months ago.Category: Mercedes
Show More
Show Less
Ask Your Own Mercedes Question
Answered in 8 hours by:
11/14/2017
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago
Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 5,740
Experience: 20 years Master Certified excellent fix rate and have access to factory wiring, and instructions.
Verified

Hello, my name is***** and i will do my best to assist you.I am going over your story now and will reply back soon with some info,thanks!

Ask Your Own Mercedes Question
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

with your issue it sounds like it can be a simple temperature sensor.

there is a cold start temperature sensor that activates the cold start injector to add the extra fuel to help start the car. OR it can be the idle air valve that is allowing too much air at idle when cold.

have they mentioned anything about those?

Lou

Ask Your Own Mercedes Question
Customer reply replied 5 months ago
The put a new cold start valve in and did not help. They did say it might be a vacuum issue but would need to take the manifold out (6 hours labor) to see if thats the problem. Is the air idle valve easy to get to and inspect?
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

no you must have misread what I said,

Ask Your Own Mercedes Question
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

the cold start injector only injects based on coolant temperature, so if the temperature sensor has failed then the cold start injector would not be activated to inject.

i will try and get you some documents that would hopefully help

the info for the old cars is not as easy to obtain but I will try.

Lou

Ask Your Own Mercedes Question
Customer reply replied 5 months ago
Okay yes that is what they put in and did not help. Unless it was a bad one. But a diagnostic would tell them that would it not?
Customer reply replied 5 months ago
Is the temperature sensor easy to get to and I put it in myself?
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

well with a car this old there was limited fault codes and diagnostic pointers.

yes the temp sensor is easy to replace.

Ask Your Own Mercedes Question
Customer reply replied 5 months ago
Its not an expensive part so maybe I will attempt it and see if that helps. Where on the radiator is it located?
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

its located on the engine, i am trying to find the location, there is a 4 pin sensor up in the front and i think this one is in the rear of the engine. on the top , near the back of the cylinder head.

Ask Your Own Mercedes Question
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

ok the temp sensor is at the back of the engine on top, mounted on the cylinder head.

Ask Your Own Mercedes Question
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

its also possible that the ground is bad to the cold start valve so keep that in mind.

Ask Your Own Mercedes Question
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

also you will want to check the overvoltage protection relay to make sure the fuse is ok and there is no corrosion in the connection.

Ask Your Own Mercedes Question
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 5 months ago

look on the top of your water pump / thermostat housing and those are temp sensors.

you are looking for the same as the smaller one near the top back of the engine.

Lou

Ask Your Own Mercedes Question
Was this answer helpful?
Ask Lou P. master tech Your Own Question
Lou P. master tech
Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 5,740
5,740 Satisfied Customers
Experience: 20 years Master Certified excellent fix rate and have access to factory wiring, and instructions.

Lou P. master tech is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry.

Stephanie PElm City, NC

used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future.

David L.Richmond, TX

9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much.

PhilMarysville, CA

Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible.

CharlesWalnut Creek, CA

As a single woman, I really appreciate an excellent and affordable opinion.
Thank you Geordie, I will not hesitate to contact justanswer in the future!

SueCharleston, WV

Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff.

JimCastleberry, FL

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

< Previous | Next >

Meet the Experts:

MB Paul

MB Paul

Mercedes Technician

3,567 satisfied customers

Qualified Mercedes Benz Diagnostic Technician - 20+ years experience - Workshop Foreman for Mercedes

Marty

Marty

Mercedes Technician

29,009 satisfied customers

Bosch Certified Master Tech. Over 35 years experience.

Lou P. master tech

Lou P. master tech

Mercedes Technician

5,740 satisfied customers

20 years Master Certified excellent fix rate and have access to factory wiring, and instructions.

Michael Warfield

Michael Warfield

Factory Mercedes-Benz Technician

3,131 satisfied customers

Mercedes-Benz Master Certified technician

Matt

Matt

Engineer

602 satisfied customers

Mechanical Engineer with 23 years experience in the auto industry, 8 yrs in formula 1 engine testing

promerc

promerc

mercedes diagnostic technician

553 satisfied customers

Qualified mercedes diagnostic technician & service team manager , ATA registered Master tech

Hipo64

Hipo64

Mercedes Technician

444 satisfied customers

Work and diagnose electronics on daily basis.

< Previous | Next >

Related Mercedes Questions
Coolant indicator fault showed up on dash, car was not low
Coolant indicator fault showed up on dash, car was not low on coolant but is maintaining a check engine light what is srong … read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
Where is the engine coolant temperature sensor located for a
Hi, Where is the engine coolant temperature sensor located for a 2007 GL450 Mercedes Benz, do you have a diagram … read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
Not getting supply power to my coolant fan module. Not sure
Not getting supply power to my coolant fan module. Not sure where to check for the source power. … read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
1996 mercedes benz c220 coolant light came on the other day
hi 1996 mercedes benz c220 coolant light came on the other day it was low added coolant to the resovior and found there is oil in the coolant ionly in the resivor and only abot 25%of the resivor is oi… read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
I have an oil leak in my coolant reservoir. Its a mercedes
Its a mercedes benz CLA 250? No I have never replaced the gaskets … read more
Eric
Eric
Retired
N/A
14,436 satisfied customers
My 2006 Mercedes C Class had coolant problems. When I had
My 2006 Mercedes C Class had coolant problems. When I had the problem fixed, which was replacing the water pump, a hose that goes under the radiator and the thermostat. Now the fan kicks in as soon as… read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
Can the C230 engine run without coolant. It's 250 000 km.
Hello JA: Hi. How can I help? Customer: Can the C230 engine run without coolant JA: How many miles on the car? How has your mileage been lately? Customer: It's 250 000 km JA: What year is your C230? C… read more
Kevin
Kevin
workshop foreman /master tech/mot tester
1 satisfied customers
Would I be able to change the coolant thermostat on a 2012
Would I be able to change the coolant thermostat on a 2012 GL 450, or is this really a shop job. … read more
vwtech0405
vwtech0405
VW Technician
Associate Degree
8,868 satisfied customers
I had a low coolant warning, check the reservoir and
I had a low coolant warning, check the reservoir and everything seemed normal so i didnt add the coolant and went out with the 2016 gl450. When returning the level of the meter started fluctuating bac… read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
I need to replace the radiator, due to coolant leak, on my
I need to replace the radiator, due to coolant leak, on my 2002 S430. Are there step by step instructions available? … read more
TIM MOHR
TIM MOHR
SHOP OWNER
Master's Degree
8,037 satisfied customers
Lou.. when I am gonna install my coolant temp sensor and
Lou.. when I am gonna install my coolant temp sensor and thermostat do I have to take the O-rings and lubricate them ? If yes , lubricate with the coolant?… read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
Lou ...can I replace coolant temp sensor with thermostat and
Lou ...can I replace coolant temp sensor with thermostat and water pump being removed? Looks like to me.. thermostat and water they seems like holding the sensor..… read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
Lou... I have a question how to bleed coolant system easy
Lou... I have a question how to bleed coolant system easy way? I never done this ... I read on forums... that some people opened the cap from refill reservoir ..than start a car and squzee the upper r… read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
GETTING COOLANT VISIT WORKSHOP.. SHOP SAYS NEEDS NEW CONTROL
GETTING COOLANT VISIT WORKSHOP.. SHOP SAYS NEEDS NEW CONTROL MODULE/FANS ASSEMBLY.. CAN I GET MODULE BY ITSELD TO SAVE MONEY? 2005 CLK500… read more
fordguy4u
fordguy4u
Automotive Tech
Vocational, Technical or Trade Scho
70 satisfied customers
Last night my 1999 SLK 230 Mercedes coolant reservoir hose
Last night my 1999 SLK 230 Mercedes coolant reservoir hose broke off. It seems somehow coolant got into the mass airflow sensor area intake because it wasn't bolted down properly the tabs are broken o… read more
Chad Farhat
Chad Farhat
Owner
Associate Degree
5,054 satisfied customers
My eps light came on and my engine light and coolant level
My eps light came on and my engine light and coolant level light. I pulled my car over because as I accelerated the engine was sounding funny. Pulled over turned off car and it wouldn't crank waited a… read more
Stephen, MBA
Stephen, MBA
Master's Degree
166 satisfied customers
I need to know where the coolant temperature sensor is and
I need to know where the coolant temperature sensor is and how to replace. I have the part … read more
Lou P. master tech
Lou P. master tech
Mercedes Technician
5,740 satisfied customers
I purchased a used car with coolant leaks. NowI have coolant
I purchased a used car with coolant leaks. NowI have coolant mixed in oil and exhaust gas in coolant system. I assume at the last I have a blown head gasket or two. Is there a way I can check if it is… read more
Wolfgang
Wolfgang
6 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x