Got 98 E300 in, starts ez cold, long, long start hot - PeachParts Mercedes-Benz Forum

engatwork · #1 10-25-2020, 01:13 PM

Sometimes it will run battery down before it will not start hot. Mileage is at about 375,xxx miles. It does have at least one bad glow plug that I'll replace. I'm thiking about pulling valve cover and take a look at the timing. I'm sure it will do better after resolving gp issues. With proper synthetic oil changes how long should original chain and guides last? Can stretched chain cause harder hot start than cold?

dieseldiehard · #2 10-25-2020, 04:50 PM

Hmmm, I seem to remember hearing of a similar problem and the IP was worn, the cold fuel pumping well but hot fuel not so well. Does that sound possible?
A test by bypassing the fuel heater, if it has one might be useful. I should know but frankly can't remember where the fuel heater is, I know the 603 better.
DDH

jay_bob · #3 10-25-2020, 04:56 PM

Be sure they didn’t put gas in it.

This happened to my 606 and it would start fine cold, but when hot, the fuel would vapor lock in the IP and lines.

GregMN · #4 10-26-2020, 12:23 AM

Carry a gallon or two of water with you. The next time it happens, pour the water over the IP to cool it. If that fixes the problem, then the IP is tired. I had this happen on a 601.

nelstomlinson · #5 10-29-2020, 12:29 PM

Quote:

Originally Posted by GregMN

Carry a gallon or two of water with you. The next time it happens, pour the water over the IP to cool it. If that fixes the problem, then the IP is tired. I had this happen on a 601.

The same thing happens with the Stanadyne pumps on my trucks when they get worn. A quart of water usually get it cool enough to start.

engatwork · #6 10-29-2020, 02:21 PM

I tried spraying water and it did not seem to make a difference. I'm going to get all the gp's working then will try again.

nelstomlinson · #7 10-31-2020, 03:56 PM

Quote:

Originally Posted by engatwork

I tried spraying water and it did not seem to make a difference. I'm going to get all the gp's working then will try again.

On my Stanadynes, it takes trickling a quart of water over the pump, taking a minute or so to do it. The water lands on the valley pan on those International V8s, and cools the valley pan, and reduces the heat coming up below the pump, so it cools the pump and its environment. Greg's suggestion of a gallon of water might be a good one. It takes a lot of water to carry away a lot of heat.

engatwork · #8 10-31-2020, 03:59 PM

Found one bad glow plug, chanel it out and have same issue. With manifold off I'll try cooling ip again after hot and see what happems. Will definitely check ip timing.

dieseldiehard · #9 10-31-2020, 08:37 PM

I was taught that throwing cold water on a hot IP can cause it to warp and making it forever useless. Learned that from Gus at the Bosch service center in S. San Francisco now he's gone so I can't confirm it. just be careful!
DDH

engatwork · #10 11-01-2020, 06:50 AM

That was my understanding too so I did not just drown it when I tried it. With 360+k miles and having run for most of those miles on homemade fuel I leaning toward get the pump to a Bosch shop.

Zulfiqar · #11 11-04-2020, 06:14 PM

Quote:

Originally Posted by dieseldiehard

I was taught that throwing cold water on a hot IP can cause it to warp and making it forever useless. Learned that from Gus at the Bosch service center in S. San Francisco now he's gone so I can't confirm it. just be careful!
DDH

Yes - it will warp it. I have seen it first hand.

Zulfiqar · #12 11-04-2020, 06:15 PM

Quote:

Originally Posted by engatwork

That was my understanding too so I did not just drown it when I tried it. With 360+k miles and having run for most of those miles on homemade fuel I leaning toward get the pump to a Bosch shop.

If you can force a glow cycle on a warm engine and it starts up smoothly after that - its a sign of a weak engine.

engatwork · #13 11-07-2020, 01:34 PM

Finally was able to spend a some time on it today. When the horizontal metal tab is lined up in the window where I removed the bolt on the side of the injection pump the engine is at 19d past TDC. Based on everything I've read it is supposed to be at 14d past TDC. Please confirm. I'm thinking it is probably time for new timing chain guides and timing chain and probably oil pump chain and chain tensioner.

I will say it is pretty easy to turn over for it to be a diesel engine. I may go ahead and pull valve cover tomorrow and look at timing a little more.

GregMN · #14 11-07-2020, 06:37 PM

With that many miles, things are wearing out. With the easy cold start, hard hot start, my guess is a tired IP. Best way to check timing/chain stretch is between the crank and the cam. The IP timing is adjustable, the cam and crank should be static except for chain wear.